21.5-inch iMac vs. 27-inch iMac: Which all-in-one desktop Mac should you get?

21.5-inch iMac vs. 27-inch iMac: Which all-in-one desktop Mac should you get?

iMac Buyers Guide: A comparison of the different versions of Apple's razor-thin all-in-one Mac desktop

Apple's iMac rewrote the company's fortunes at a time when Apple desperately needed a hit. The year was 1998. Steve Jobs had returned to take the helm of the ailing company, but Apple had spent years churning out poorly-differentiated beige boxes. Out comes a translucent blue all-in-one computer unlike anything else on the market. It sold like wildfire and set off a design renaissance in personal computing: within a couple of years, everyone was churning out colorful, cheerful PCs that mimicked Apple's hit system.

Fast forward to the modern day: the iMac has undergone some radical changes. Gone is the translucent case; gone is the bulky CRT display. In their place is an incredibly elegant flat panel all-in-one design that has gotten progressively thinner over the years as Apple has done everything it can to get the computer itself out of the way of the computing experience. Within the iMac product line, however, there are a lot of options to consider, so let's take a look at what Apple is offering.

Comparing iMac models

Though the iMac comes in two different form factors, both of them are similarly equipped, so let's take a look at what they share. On the back, you'll find a digital headphone jack, SDXC card slot, four USB 3 ports, two Thunderbolt ports and a Gigabit Ethernet port.

Interestingly, you can use a Thunderbolt port to power an external display at up to 2560 x 1600 pixels. So you can hook up a 30-inch display to your iMac and have a smokin' multi-monitor system. The iMac also supports something Apple calls Target Display Mode, which lets you use the iMac as a monitor for another computer: for example, if you wanted to use your iMac as a big display for your MacBook Air.

Also included is 802.11ac Wi-Fi networking - the faster standard that Apple's migrated most of its systems to in 2013 which provides up to three times the data transfer speed of 802.11n. Bluetooth 4.0 also comes standard. A FaceTime HD camera is built into the bezel of the iMac.

In the fall of 2013, Apple refreshed iMacs with the faster Wi-Fi protocol and Intel's fourth-generation Core "Haswell" processors. While Haswell's main claim to fame has been dramatically improved battery efficiency on laptops, it has some practical applications for iMacs too: improved efficiencies increase overall CPU performance, and integrated graphics performance is significantly better than before: enough so that Apple chose to use them for the first time in the low-end iMac (more on that in a bit).

Apple's 21.5-inch iMacs make up the low end of the iMac product line. The 21.5-inch iMacs measure 20.8 inches wide and 17.7 inches high. They take up less than 7 inches of desk space from front to back; considering the screen size, they're really compact machines that can fit in a wide variety of environments.

The base model is a $1,099 21.5-inch iMac with a 1920 x 1080 pixel display, 1.4 GHz dual-core i5 processor, 8 GB RAM, 500 GB hard drive, and Intel HD 5000 integrated graphics. For $200 more you get a 2.7 GHz quad-core i5 processor, 8 GB RAM, 1 TB hard disk drive, and Intel Iris Pro graphics. For another $200 ($1,499), the 21.5-inch iMac gets a faster 2.9 GHz processor and faster Nvidia GeForce GT 750M graphics, with 1 GB of dedicated video memory.

The 27-inch iMac is bigger all around than the 21.5-inch model. It's 20.3 inches wide and 25.6 inches high, and stands about 8 inches deep on a desk. Its size may make it a slightly less flexible system to put anywhere you want, but it's a great machine on a desk, in a bedroom or a family room, and the 27-inch display can be big (and beautiful) enough to double as an entertainment system when it's not in use for something else.

The 27-inch iMac starts at $1,799. That gets you 2560 x 1440 display - the same size and resolution as Apple's Thunderbolt Display, only much thinner. A 3.2 GHz quad-core i5 processor is accompanied by 8 GB RAM, and a 1 terabyte (TB) 7200 RPM hard disk: that's faster than the 5400 RPM model included on the 21.5-inch machines. Nvidia GT 755M graphics come standard on that model. And for $200 more, you can get a 27-inch iMac with a 3.4 GHz processor and faster Nvidia GeForce GTX 775M graphics, with twice as much dedicated video memory: 2 GB.

To get a sense of how the different screens compare more directly, look at this image. The smaller rectangle is proportional to pixel resolution of the 21.5-inch iMac. The larger rectangle is proportional to the resolution of the 27-inch iMac.

27 inches is gobs of desktop space, by the way. It's easy to lose your cursor on a screen that big with that high resolution. You can have an enormous amount on the screen. It may not be a Retina display, but don't forget - even on a 15-inch Retina MacBook Pro, the resolution is scaled to a maximum of 1920 x 1200. 2560 x 1440 is a lot more space.

Both iMacs can be wall-mounted using an optional VESA adapter, but you'll need to decide this before you buy it - this is a configure-to-order option only. iMacs built before 2012 could be adapted to VESA wall mounts after the purchase by partly disassembling the case and removing the stand.

All iMacs include the Apple Wireless Keyboard and Apple's Magic Mouse. All iMacs also come standard with Apple's suite of consumer software: OS Mavericks and all the software normally included with that installation, along with iLife '13 - iMovie, iPhoto and GarageBand; as well as iWork '13 - Pages, Numbers and Keynote.

Let's drill down a bit and how you can custom-configure your iMac to make sense for what you're doing, specifically.

i5 vs. i7: Not all quad-core processors are the same

All iMacs except for the low-end $1,099 model come equipped with quad-core i5 processors - processors that can run up to four sets of instructions simultaneously. That makes them better at running applications designed to support parallel processing. Computationally-intensive software like scientific apps, 3D modeling, data transformation, even video and audio encoding (like ripping videos from DVDs or music from CDs) all benefit greatly from more cores. The low-end model, with its lower clock speed and dual-core design, isn't going to be up for the same sort of heavy lifting as its quad-core counterparts.

The high end 21.5-inch and 27-inch iMac models can be custom configured with better processors for an extra $200. The 21.5-inch model gets a 3.1 GHz quad-core Intel i7 processor. The 27-inch iMac gets a 3.5 GHz i7 processor. Not only are the clock speeds on the custom configurations slightly higher than the stock processor (with correspondingly higher burst speeds), but the i7 processor also gains an Intel technology called hyperthreading, which can make parallel processing even faster.

Apps that are optimized for OpenCL, an open standard parallel-processing framework, will benefit from the i7 processors. What's more, the discrete graphics processors on those higher end systems (GPUs like the GeForce graphics on all but the lowest-end iMac) are parallel-processing monsters. Apple's own Final Cut Pro X is an example of an OpenCL app.

Bottom line: if you plan to be doing a lot of data transformation or encoding or performing other tasks, consider bumping up the processor. For everyone else, a quad-core i5 processor clocked at the stock speeds is plenty fast for whatever you might be doing.

The dual-core on the low-end system isn't limiting for casual users who just want to surf the web and use the iMac for general purpose stuff. If you plan to do professional work on your iMac using apps that support multithreading, however, you're going to run into a CPU bottleneck pretty quickly.

Upgradable versus non-upgradeable: iMacs and RAM

8 GB comes standard on all Mac models. 8 GB is twice what the Mac mini and MacBook Air come with, along with some MacBook Pro models. The 21.5-inch iMacs can be pre-configured by Apple with up to 16 GB of RAM while the 27-inch models can be pre-configured to run up to 32 GB RAM. That's because the 27-inch iMac has four separate slots that can accept RAM - twice as many as the 21.5-inch iMac.

How much RAM you need is entirely dependent what you'll be doing with your iMac, but just remember that RAM is one of the principle performance bottlenecks on your Mac. More RAM means less paging to disk with swap file data, created when your Mac has to fall back on virtual memory to work.

More RAM means you can operate more apps simultaneously without taking a performance hit and work with larger files without taking a performance hit. If you're planning on working with big Photoshop files, more RAM is a bonus. If you're planning on editing video, more RAM can help. If you're planning to use your iMac as a Digital Audio Workstation (DAW) with Garageband or Logic, more RAM will help.

There's a key difference between the 21.5-inch and 27-inch iMac worth noting. Only the 27-inch model has easily user-accessible RAM. There's a removable panel on the back of the iMac, underneath where the stand meets the display, where you can put in more RAM yourself.

The 21.5-inch iMac, by comparison, doesn't have any such door on it. Now, the 21.5-inch iMac's RAM isn't soldered - it's on modular, removable SO-DIMMs, just like on the 27-inch model - but to get to it, you have to almost completely disassemble the Mac. It's something only a trained technician is really qualified to do.

Installing RAM in the 27-inch iMac, meanwhile, is trivially easy - so easy, in fact, that Apple provides instructions on its web site. Pop a button underneath the memory compartment door and it opens. It's best to put RAM in pairs, because that doubles the memory bandwidth from 64 bits to 128 bits. That provides a bit of a performance enhancement (Apple installs memory in pairs in all iMac configurations).

My advice is to order the 21.5-inch iMac with whatever RAM you're going to need, and suffer with Apple's still RAM price penalty. On the 27-inch iMac, buy it stock, and shop around - you'll be able to do much better than Apple's price from reputable RAM vendors that sell Mac-compatible products.

Hard drive vs. Fusion Drive vs. flash storage: Balancing price, performance and capacity

1 TB of hard disk storage comes standard on all iMac configurations except the low-end. Two different types of hard disks are used on the different models: 21.5-inch iMacs get a 5400 RPM disk, while the 27-inch models get a higher-performance 7200 RPM disk. A hard disk spins around a central spindle just like the tire on the car. The difference in rotational speed means the faster drive can read and write data that much faster.

Storage options on the 21.5-inch iMac include a 1 TB Fusion Drive or a 256 GB flash drive, each for $200; or a 512 GB flash drive for $500. Any way you slice it, you're going to pay more for the same or less space - albeit much faster.

Options on the 27-inch iMac are a bit different: you can get a 3 TB 7200 hard drive for $150; a 1 TB Fusion Drive for $200 or a 3 TB Fusion Drive for $350; a 256 GB flash drive for $200, 512 GB fiash drive for $500 more, or take it all the way to 1 TB of flash storage for a very steep $1,000.

You know better than anyone what your storage needs are, and if you're coming from a laptop, it's entirely likely that 1 TB is significantly more than you had before. Having said that, stuff piles up quickly. Start editing media files on your iMac and you can run out of space very quickly, so if you're buying a 27-inch, that 3 TB upgrade can make sense.

Fusion Drive is a hybrid technology that combines 128 GB of flash storage with a hard drive mechanism, combined into one logical volume. Files that are frequently read from and written to disk remain on the flash drive, which files that are only infrequently accessed are stored on the hard drive. Anything you do that involves disk access - reading and writing files, even operations that require the Mac to page out virtual memory to disk - are going to be quicker on a Fusion Drive or a pure flash drive. It's a nice way to get the performance improvement of flash storage - which is huge - without paying the stiff premium that you do by going with pure flash.

Also, don't forget that your iMac is equipped with two Thunderbolt connections, so if you outgrow what the iMac comes with, you can attach external storage without a big hassle or a big performance penalty.

My recommendation is to consider your storage needs ahead of time and figure out just how much space you actually need. Pure flash is hard on the wallet. If you're looking for better-than-average performance without paying a huge penalty, go with the Fusion Drive options. Just bear in mind unlike a laptop, it's not a huge inconvenience to add external storage to a desktop-bound iMac - it's not going anywhere.

Integrated vs. discrete graphics: Not your average Mac

The lowest-end 21.5-inch iMac sports an integrated graphics processor called Intel HD 5000. It's a similar CPU and integrated graphics setup as the MacBook Air, and it's fine for general use, though it'll be slower if you want to play games or do other stuff that taxes the Mac's graphics system.

The $1299 iMac has Iris Pro graphics - it's also built onto the Intel hardware. "Integrated graphics" gives some experienced computer users the perception of sluggish hardware that's incapable of keeping up with even routine tasks, but that's changed a lot in this generation of Intel hardware - Iris Pro graphics are quite fast, which is why Apple decided that the $1299 iMac didn't need its own discrete graphics chip anymore.

Integrated graphics differ from discrete graphics in a few key ways. One of them is that integrated graphics use the Mac's own system memory - drawing from that 8 GB well of memory that comes standard on all iMacs. Discrete graphics chips use their own dedicated video RAM instead - it's usually faster than the system memory. The Iris Pro graphics on the low-end iMac actually has 128 MB of embedded DRAM (eDRAM), which make its memory operations work considerably faster than the integrated graphics on other Haswell processors.

Nvidia graphics on the rest of the iMac line get progressively faster and more capable with each different model. At the top of the food chain, Apple's $1,999 27-inch iMac has a system equipped with 2 GB of VRAM - twice what the rest of the iMacs get. What's more, there's a $150 option to get Nvidia GeForce GTX 780M graphics with 4 GB dedicated video memory. If you're looking for ultimate graphics horsepower on the iMac, that's the system to get.

Bottom line: The Iris Pro on the $1,299 iMac works faster than the discrete graphics on last year's model; it's a solid upgrade that users on a tight budget shouldn't be afraid of. It can't hold a candle to the Nvidia graphics on the rest of the iMac line, however.

Who should buy the 21.5-inch iMac?

The 21.5-inch iMac may be the lowest-priced iMac, but it's got plenty of horsepower to get a lot of work done. It's a great everyday computer - it can run anything you can throw at it with aplomb, and with a bit of extra memory and a tweak to the storage system can be a top performer for really intensive apps.

The more compact size of the 21.5-inch iMac makes it better suited to environments where space might be restricted - smaller desks, counter space and small apartments. The lower cost comes with a few shortcomings - a slower hard disk, fewer customization options - but don't let a limited budget or concerns over space dissuade you from the iMac. It's a fantastic Mac.

Just bear in mind that the 21.5-inch iMac can't be opened as easily as the 27-inch model, so order it with as much RAM as you need.

Who should buy the 27-inch iMac?

Short of the Mac Pro, the 27-inch iMac is the fastest Mac there is. Even Retina MacBook Pros that cost a lot more don't work as fast. The combination of speedy processor, speedy storage and tons of desktop space make the iMac the most versatile and powerful Mac you can buy without spending $3000 or more.

Not everyone needs the horsepower or screen real estate of the 27-inch iMac. But those that do get a premium experience - a fast Mac tuned for maximum performance, all in an elegant enclosure that's part sculpture, part machine.

Still undecided?

If you still can't make up your mind about which iMac to purchase, that's okay. Our iMac discussion forum is a great place to ask for help. You're welcome to post comments here, too.

Peter Cohen

Managing Editor of iMore, Mac and gaming specialist and all-around technologist. Follow him on Twitter @flargh

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21.5-inch iMac vs. 27-inch iMac: Which all-in-one desktop Mac should you get?

24 Comments

As usual, great insight with regards to comparing these two systems and weighing in on practical assessments for which could be the right machine for the right user. Thank you Peter.
As for me, I've been abusing a 24" iMac for over 5 years now. The 27" model is what I have my eye on. For the 3S rendering, digital art, and occasional DAW usage I get involved in, I, just like Tim "The Toolman" Taylor, can always use more power! I will need the i7 & at least 16 GB RAM. I get all giddy just thinking about 4 GB of VRAM! The Fusion drive sounds rather appealing - of course I want the 1 TB Flash storage, but... Unless I come into some money, it won't happen.

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I think 27" gives you more space to have more items open side by side. Great article and comparison of the two sizes.

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With all  products i recommend going Full TILT - because if you keep your products they will have most longevity, where as lower end see the chopping block first.

Plus the 21 inch units are NOT upgradeable - you have to pay up front for any future needs.

I just got my 27inch fully loaded 3tb fusion iMac - i had it for 10 days and got my ram from 3rd party - ended up having apple upgrade to the 16 GB because it's 2 chips - then got 3rd party ram for the other two slots - the reason is if there is any issue i don't have to store and find 2 - 4gb chips that I don't use just incase there is an apple care issue you'd have to use the original chips -

on day 12 i had returned the entire thing to apple store - because the third ram slot was defective - wouldn't read ANY ram installed - wouldn't even boot.

They swapped it out for a brand new identical unit - got it home and added the ram for a total of 32gb - love it!
best mac ever!

The other reason why i say go full tilt is that its has a better resale value when it's time to sell - just look at crags list and ebay with tones of 21inch units that are stuck at 4gb or 8gb ram because thats all they purchased with it. if you could just bump the ram on those machines they'd be actually worth something.

Actually....as an owner of about a dozen iMacs over the past decade, I can tell you from experience, the lower the price you pay up front, the more return on your dollar. As time moves on, storage and memory prices come down....as well, Intel's CPU performance goes up. I just sold the bare bones 2009 21.5" iMac for $825 on craigslist locally. That's. Unreal! Got $800 for an '08 model this time last year. We use these 'Low End' models (I quote because we ALL know Apple doesn't make cheap;))---as our primary music and lighting/DMX control systems for my mobile entertainment company. We did 112 weddings this year and we're currently buried in holiday (corporate) parities. These new iMacs....at Best Buy last week were $200 off! $1099 for the low end guy with an 800GB sound library....everything fits easily on board, they're cheaper than the laptops (my personal machine is an rMBP that terrifies me having out at a 'party' where any idiot requesting a song could pour a beer on it and the library is stored externally on an $80 HDD...). They weigh 12 pounds! They're HUGE in comparison to the laptop displays (I'm 42 and anything 'bigger' is easier to see!). And for what we are doing....accessing the iTunes library, they haul ass!
That said....I've got a MacPro, 2010 as my home, primary video and audio editing machine. Once the new MP hits and we've got a bit more knowledge on Apple's display options...I'm seriously considering that 27"/32GB/3TB fusion with the 780!!!! Course, she'll stay home!
Lastly, oceanwest....this (& last year's redesign) iMac are the exceptions to the rule. Pre 2012, the 21.5" iMac was also easy to upgrade the RAM....Built with the identical door with four scews like the 27---- it was a very easy process. I'm not a fan of inaccessibility to the HDD and RAM....But that's what Applecare is for, right? B&H, eBay and Amazon all offer Applecare at almost a 33% discount (I think I paid $225 instead of $349 on my new rMBP) and as certified Apple resellers, it's legit....they actually activate it for you (B&H anyway) & then ship the box to ya.

Thanks for the review. Very well done

Jeremy

Excellent write up as always, Peter. iMacs are really a thing of beauty. If you're not as familiar with Macs like I was before you really wouldn't expect that inside that eye-catching gorgeous design is a powerhouse waiting to be unleashed. I can only imagine playing my favorite games on a maxed out 27" iMac with the big display and that GTX 780M (drool).

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I own a 2011 27" iMac, and one thing articles never mention is that OSX fonts don't scale very well when it comes to larger displays and higher resolutions.

On paper, a larger screen sounds like a better thing. More space to display your files and get work done, right? In practice, you will find that fonts appear quite small on that 27" screen, and there is no way to enlarge them, so you either have to remember which does what, or keep squinting to make them out.

Also, another irritating thing is that documents appear quite small, and I find myself often having to zoom my documents to 200% to be able to read it comfortably. This leads to some interesting situations where I then email the document to my colleagues and the documents appear all blown up when they read them on a normal display. That said, such a huge screen is a godsend when I am working on excel documents and can viewing everything on the same page without having to keep scrolling everywhere, or on a word document where I can view up to 3 pages side-by-side (compared to a 22" screen where the threshold is 2 pages side-by-side for me).

Another irritating thing - Safari doesn't remember your zoom preferences, so with every new page, you have to keep hitting cmd+plus if you want to enlarge the browser (and you will want to do this often, as mentioned, pages can appear too small). Chrome actually remembers your default zoom settings for every webpage you visit though.

Lastly, if you plan on gaming on that 27" monitor, do yourself a favour and upgrade the graphics card to at least 2gb. My iMac had the 512mb card, and it's struggling to run desktop games in native 2560x1440 res (and blowing 1080p up makes the graphics look like crap). I ended up running games like Darksiders2 in 1920x1080 windowed mode, and I still have to turn some settings down so it won't lag.

Basically, do consider if you need the horizontal screen estate more, because if so, a 21" iMac and an extra monitor might fit the bill better. Just my 2 cents. :)

I don't quite understand why they made the iMac so much thinner at the expense of an optical drive. I think that optical drives are still quite useful, and thinness in an iMac is less relevant than in a MacBook since one looks at the front of it and does not carry it around.

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Fewer and fewer people need access to optical drives with the rise of cloud storage and streaming services. And for those that do, Apple offers an external SuperDrive for $80.

My iMac is getting a little long in the tooth, but the thing that keeps me from upgrading is the audio inputs on the current iMacs. Mine has separate optical input and output, the input to which I have my XM-PCR receiver and the output going to my Logitec speaker system. This is impossible with the new iMacs. A Griffin iMic might solve the problem but it uses up a valuable USB input. Also I have a 1 TB Firewire 800 drive I use for Time Machine. Are there any 1 TB Thunderbolt drives available? Probably are, I just haven't looked. This thing is still working well with Mavericks, so I will wait a while.

Yes....thunderbolt externals are available and an external sound card, something like the $30 UC202 from Behringer will give you a LOT better sound quality doing your DAC externally without the 'noise' associated with an internal headphone DAC. You can always spend more, DACs can go up to a thousand dollars +, but for what you're looking for I think you'll be happy with the Behringer. It's got in, out...as well as a toslink (digital) in/out as well as a phono boos if you want to plug in a turntable. The iMic, while it's an excellent travel companion is limited to in OR out. One or the other and without a digital connection
I'm not a fan....but any of the pro tools specific DACs are pretty good too, albeit more expensive.

As a first-time Mac owner (in 2011), I was quite torn between the iMac and the Mac Mini. I ended up going with the Mac Mini. It made more sense for me because my old HP desktop had finally died and I was ready to move on. Also, I already had two ViewSonic LCDs, the Keyboard and wireless mouse and external speakers.

I would recommend to anyone who is looking to move from PC to Mac to seriously consider the Mac Mini. It is a GREAT computer and comes in both the Core i7 and i5 flavors. It's the lowest cost Mac, but does not skimp on quality of performance. After buying it, I upgraded my Mini to 8gb ram and a shiny new Samsung SSD and now it's way faster!!!

I bought a copy of Parallels Desktop 9 for it and I have a Windows VM installed. I am a software developer and as such I need to develop for not only the Mac but for Windows, so I need both operating systems.

To sum it up, if you already have the monitor(s), speakers, keyboard and mouse, then seriously consider the Mac Mini and run by your local electronics store and pick up any 3rd party external-usb DVD drive if you still use DVDs (like I do).

Don't underestimate the capability of this little desktop powerhouse!

Quite simply! The Mac Mini JUST WORKS!

Just kinda sad they were left out of the Haswell update....so far. Maybe when the MP drops, the new Mini will join it (along with display releases). That said, ivy bridge is still a fast processor...but the Intel 4000 (iGPU as discussed in the review) in last year's mini gets it's clock cleaned by the new Haswell iGPU options, including the Airs released this spring. If it's a Mini you want....wait a bit til the Pro drops and see of it's accompanied by the new batch of Minis. I'm with you....it's a damn good computer.

I think the iMac is a great computer. I still have my mid 2007 iMac that runs Mavericks and is snappier than ever before. My former roommate had his eMac (remember that) for 11 years. When it comes to computer hardware nothing comes close to Apple. If I do upgrade I will wait till the Retina display iMac and who knows by then I might actually need to upgrade.

Just bought basic 27" for work, new job will be tele-practice health care via Skype ! Do you all think that's enough of a computer for that purpose ?

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Continued from above:
Apple 27" iMac - 3.2GHz Intel i5, 1TB HD, 8GB

I will be using web based program and database and Skype ! The above is good choice ???

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Absolutely! You have a fine machine that's sure to work for years to come. I'm jealous, actually...my iMac is almost seven years old! :)

Another great comparison Peter. While I have a loaded 27" for audio/video/photography, I am always unsure what to recommend to others. Your assessment provides a great perspective.

I like at least 24 inches for a desktop and the 27 inch is expensive. I will probably connect an external monitor to my MacBook Pro.

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I agree Lance, 24 inches seems the ideal size. I've owned/managed at least 15 iMacs at home and work from the original to today's model. In that time we've had one 24" iMac and to this day I like it the best.

Mine is a 27-inch 2010 iMac with 2.93 GHz Intel Core i7, 12 GB 1333 MHz DDR3 RAM, 1TB HDD. Attached is a 24-inch Asus 1080p Display.

I don't know why others don't step up their game on the Display like Apple does. I have a nice 2560x1440 display on my iMac, and every one else is topping off at 1920x1080.

Thanks for pinpointing the new features that came with the Sept 2013 edition of iMacs. I was looking for screen resolution in terms of pixel per inch, which you don't specify and which seems to me the best technical feature for photographic display. I calculated a resolution of 109 dpi for the 27 inch screen and 102 dpi for the 21.5 inch screen. For that I had to find the side dimensions of the true screen, not the frame dimensions which you seem to specify for space consideration. There seems to be an error in your data: the 27 inch screen cannot measure 20.8 inch in width. The active screen should be 23.5 x 13.2 inch for the large screen, and 18.7 x 10.5 inch for the small one if their aspect ratio is 16/9 as the pixel count indicate.