The 27-inch Apple iMac Review (2011)
by Anand Lal Shimpi on May 27, 2011 2:30 AM ESTThe GPU
There are four discrete GPUs Apple offers in the new iMac and they're all from AMD, NVIDIA is completely out of the 2011 Apple lineup at this point. The entry level 21.5-inch iMac has the same Radeon HD 6750M as the upgraded 15-inch MacBook Pro. You can get a higher clocked 6770M in the upgraded 21.5 and base 27-inch models, and finally only the upgraded 27-inch iMac comes with a Radeon HD 6970M.
| GPU Options | |||||
| AMD Radeon HD 6750M | AMD Radeon HD 6770M | AMD Radeon HD 6970M | |||
| Manufacturing Process | 40nm | 40nm | 40nm | ||
| SPs | 480 | 480 | 960 | ||
| Texture Units | 24 | 24 | 48 | ||
| ROPs | 8 | 8 | 32 | ||
| Core Clock | 650MHz | 725MHz | 680MHz | ||
| Memory Bus Width | 128-bit | 128-bit | 256-bit | ||
| Memory Clock | 900MHz | 900MHz | 900MHz | ||
| Frame Buffer | 512MB GDDR5 | 512MB GDDR5 | 1024MB GDDR5 | ||
The 6970M doubles the number of shaders to 960 and doubles the memory bus width to 256-bits. The result is a GPU that has the fillrate and memory bandwidth to actually drive the 27-inch 2560 x 1440 panel...on sufficiently light games.
It's not all about compute and bandwidth, memory size matters as well. Unfortunately other than the upgraded 27-inch system, everything else only ships with a 512MB frame buffer. That's enough to drive the integrated panel but if you're running a high resolution external display as well you may notice some slowdown.
The upgraded 27-inch iMac can also be outfitted with an optional 2GB frame buffer for an extra $100. The added GB is nice but likely only useful if you have a specific application need or are running multiple displays.
| 2011 iMac GPU Comparison | ||||||
| iMac Model | $1199 21.5-inch | $1499 21.5-inch | $1699 27-inch | $1999 27-inch | ||
| Base GPU | AMD Radeon HD 6750M (512MB) | AMD Radeon HD 6770M (512MB) | AMD Radeon HD 6770M (512MB) | AMD Radeon HD 6970M (1GB) | ||
| GPU Upgrade Offered | None | None | None | AMD Radeon HD 6970M (2GB) | ||
Apple sent us the upgraded 27-inch model because 1) I asked for it and 2) Apple thinks I really care about performance. Both are indeed true. The question I wanted to answer was whether or not the Radeon HD 6970M was going to be sufficient for panel-resolution (2560 x 1440) gaming on the 27-inch iMac both now and in the future. I don't have any older iMacs handy so unfortunately we'll have to do our GPU comparisons to the MacBook Pro line.
We'll start with Half Life 2 Episode 2. A game that's definitely long in the tooth but still represents a good workload for a Source engine game on Steam. It doesn't make sense running at resolutions below 1680 x 1050 on a 27-inch panel and thankfully the 6970M does a good job here:
While even the Radeon HD 6750M can manage a respectable 73.9 fps in our test, the 6970M offers nearly double that at 139 fps.
| Half Life 2 Episode Two High Quality Settings | |||
| 2560 x 1440 - 4X AA/16X AF | |||
| 27-inch iMac (Mid 2011) - AMD Radeon HD 6970M | 112.8 fps | ||
Running at native panel resolution, the 27-inch iMac is still very playable under Half Life 2.
Moving to a more modern Source engine game: Portal 2, shows that yes you still get playable frame rates at low and high resolutions although maxed out I could only manage 60 fps on the iMac. This is far superior to the 6750M which struggles at our highest quality settings, but at 60 fps there isn't much room to grow in game complexity before the 6970M begins showing its limits.
In fact we already see those limits with Starcraft 2:
| Starcraft 2 - 2560 x 1440 - Ultra Quality Settings | ||||
| AT CPU Bench | AT GPU Bench | |||
| 27-inch iMac (Mid 2011) - AMD Radeon HD 6970M | 37 fps | 51 fps | ||
37 - 51 fps isn't the sort of buttery smoothness we've come to expect from a high end Sandy Bridge system running this game. It is very tough to drive the number of pixels we're talking about at native panel resolution. Thankfully for a game like Starcraft 2, as long as you're above 30 fps you're in good company. Drop the resolution to 1680 x 1050 and the 6970M looks a lot better:
I threw Windows 7 on the machine to put its GPU performance in perspective. Looking at Metro 2033 performance you get a good idea for where the 6970M falls compared to the performance mainstream to high end desktop GPUs we talk about regularly:
Overall performance is comparable to that of a GeForce GTX 460, which is still a great card - just not what we'd pick for driving a panel of this resolution. This is ultimately my issue with the GPU choices Apple offers with the new iMac: they are fast enough for most gaming on the Mac today, but likely aren't enough for panel resolution gaming for anything more strenuous (without dropping image quality). You can forget about most modern titles under Windows at panel resolution.
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KoolAidMan1 - Sunday, May 29, 2011 - link
iMacs don't use mobile CPUs. My gaming PC and my 2009 iMac have the exact same CPU, a Core i7-860boop - Saturday, May 28, 2011 - link
anand, i used to have the same dilemma you face regarding the syncing of files across multiple machines. i even did the same thing as you and tried to use an macbook pro as a desktop replacement. it didn't work out so well. a notebook that's powerful enough to be a desktop replacement isn't portable enough -- and a notebook that's particularly portable just isn't powerful enough to be a desktop replacement.The solution I found was to use google docs and other related online services to store all my work files. as you know you can access the files on any machine, and even be logged in on multiple machines simultaneously; documents can be shared with others for collaborative work; and it also solves the problem of data back ups and laptop theft since nothing is locally stored. my current Mac setup is a 13" macbook pro and the 2011 21.5" base model imac and with all my work stored in the cloud i've finally found an optimal solution to my workflow woes. hope this helps!
ananduser - Saturday, May 28, 2011 - link
Apple packages tech real well. Good display, reasonable PC, all'n'all a good looking AIO that especially does not compromise on the display side of things. Glad I am not in need for the OS or the hardware flexibility of the laptop combined with the mobility of the desktop.Even if Apple gets so much marketing coverage everywhere I am still glad that I see my own kind keeping criticism alive.
Hrel - Saturday, May 28, 2011 - link
That display is worth 400 bucks tops; it's insane to me that anyone would pay a grand for a display barely above 1080p. I can get a good ISP 27" 1080p display for 300, so that thing is worth 400 tops; which makes that whole system 300 dollars too expensive to even consider. Then there's all the laptop parts and non-upgradeability and Appleness to ruin the experience.Kristian Vättö - Saturday, May 28, 2011 - link
Find a similar display for 400$ then. It's ridiculous to argue that the display can't be worth more than 400$ when similar displays cost 1000$. If you don't think it is worth it, then that is your thing. It doesn't change the fact that the display is worth ~1000$.I also doubt that you can find a good 27" IPS display for less than 300$. Most of the good ones are either ~22" at that price range or you have to pay more.
donnyg - Saturday, May 28, 2011 - link
You can get a Hazro, which is literally the same panel as the current Apple CInema Displays minus the aluminum casing, for around $500 USD.Shipping will make it cost considerably more however.
KoolAidMan1 - Sunday, May 29, 2011 - link
There is a massive different in pixel density between a 27" display at 2560x1440 and 1920x1080, HUGE. Then there's the fact that your display is using a crap TN panel instead of an IPS, isn't LED backlit, etc etc.A good 24" IPS display from HP or Dell is going to cost $400-$500, and a 27" with the same panel from Dell or NEC is going to cost $1100-$1400.
For a site with a "techie" readership, it is amazing how little some people know about tech, or how much they are willing to excuse purely based on price. Yeah you can save money on a cheaper display, but it is going to be totally inferior in every way except for price. You get what you pay for.
MadMacMan - Saturday, May 28, 2011 - link
That's exactly right. DO YOUR RESEARCH, people. There is NO equivalent in the 27" category of HIGH-END displays and by that I mean not part but ALL of the following:LED back lighting (No CCFL bulb, thank you), in-plane switching (IPS); not your average (READ: average, as in mid-range, as in lame, as in cheap, as in what a lot of you might buy and post BS about how you're not getting ripped off by Apple because you're so much smarter; you know who you are). Finally, and perhaps even more problematic to find is its high RESOLUTION! 2560x1440. That's 78% more real estate than you get on a standard 1920x1080 display.
I dare anybody to Google me up a 26"-29" monitor with the aforementioned specs, but ALL of them, not one or two. Now go to Best Buy and buy yourself a cheap HP or order up an Acer and make sure you don't forget to rub it in. ;-)
donnyg - Saturday, May 28, 2011 - link
http://www.hazro.co.uk/HZ27WA.phphttp://www.hazro.co.uk/HZ27WC.php
IPS monitor: Check
2560x1440 resolution: Check
LED backlighting: Check
Price: 569 AUD for the the one with extra inputs/scalar,
Kristian Vättö - Sunday, May 29, 2011 - link
I don't know where you got your 500$ as 443£ is equal to 731$. That seems to be without shipping. Cheaper? Sure, but not that much.You can always save a few bucks if you do some shopping and build it yourself. The iMac, or any Apple product, has never tried to be the cheapest option or best bang per performance on the market. I would still say the new iMac is great value. I already mentioned why an OEM PC and a homebuilt one are not always comparable, especially when we get into an Average Joe level. Hardcore gamers will never be satisfied with Apple's offerings but to be honest, I don't get it why they complain then. Nobody is trying to sell them an iMac.