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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joe_dude - Saturday, May 28, 2011 - link
But the thing's essentially a 3-year old PC. Why the heck would I want to pay more to downgrade?Of course Macs hold their resell value... it's not for gaming, so even a 5 year old Mac seem pretty fast using regular apps.
Even if it can be used as just a monitor, who the heck wants the extra dead weight? All-in-ones will always be a compromise. The point of having a desktop PC is *not* to compromise. Otherwise, a laptop can do the job.
Kristian Vättö - Saturday, May 28, 2011 - link
Good luck finding a Sandy Bridge CPU and AMD 6000-series graphics in a 3-year-old PC.A LOT fits between regular apps and gaming. Photo, music and video editing are the first that come to my mind. For some people, Macs are the preferred option due to Logic and Final Cut. When you don't have the $ for Mac Pro, iMac is your best option. In the end, iMac is far more powerful than MBPs or other laptops.
Sure, AIO form factor has its downsides but it's pretty clear that Apple has never been interested on enthusiasts. For an Average Joe, iMac is a brilliant machine, which explains why it sells so well too.
joe_dude - Saturday, May 28, 2011 - link
Don't be hoodwinked. Any 3-year old SLI rig would beat the pants off this thing. Remember, it's a _mobile_ CPU with a _mobile_ GPU; a laptop pretending to be a desktop.Any middle-of-the-road SFF/ITX machine with a Radeon 6850 would beat the pants off this thing. This thing is all about form over function. Save the money and get a 30" Dell monitor instead.
Kristian Vättö - Saturday, May 28, 2011 - link
I would like to know where you can find a 3.4GHz quad core mobile CPU. The CPUs are standard desktop parts and i7-2600 is actually one of the fastest CPUs that is available today.Your 3-year-old SLI rig beat or come close in GPU performance but the iMac would run circles around it in CPU bound tests. If you talk about performance, then you must include every area, not just gaming and graphics tests. Or then specify that you are only talking about gaming performance.
iMac's value isn't that bad when you consider the value of the screen. 30" monitor will cost you at least 1000$ so that leaves you another 1000$ for the actual computer. Sure, that is more than enough to get the similar components but the iMac won't end up being more than ~200$ more expensive (which is pretty good when talking about Apple).
Nobody is forcing you to buy an iMac so that is why I don't get why you are complaining. Clearly, there are people who want one, even if it is a compromise. You can stick with your PC if that is what you prefer.
joe_dude - Saturday, May 28, 2011 - link
Ah yes, you're right on the CPU. For some reason I thought the dual channel 1155 socket meant it was a mobile CPU.The Dell version of the 27" can be had ~$800. Of course, retail price is ~$1000, and Apple wouldn't charge less, of course.
The 3.4 GHz i7 option costs extra (is it really $500???), so we're talking a ~$1700 PC (sans monitor). We're talking a full out i7 SLI rig vs. a weaksauce iMac for that price.
I'm a gamer, but not crazy enough to spend that on an all-in-one!
Kristian Vättö - Saturday, May 28, 2011 - link
I think you should really check your facts before you post. The i7 option in iMac is 200$, not 500$. Sure, it is still overpriced but BTOs in general are. The iMac can also be had for less when you look at resellers like MacMall so IMO, the only fair comparison is to look at retail prices.For 1200$, you can build a nice PC but definitely not an SLI system (unless you go with lower-end GPUs, though that kills the idea of SLI IMO).
If we wanted to be fair, we should compare the iMac to an OEM PC, not self-built one. Why? Because you are paying for the labor and service in the iMac as well. That is why OEM PCs cost more than the ones you build on your own. I know the joy of building your own computer is unbeatable and I love it too but when comparing things, you have to understand where the costs come from. It's a whole new question whether it is worth it for you to pay the extra for service etc.
I'm not trying to sell you an iMac but to make you understand where the costs come from and in the end, why the iMac isn't that bad value. For gamers, the iMac is and will always be a very compromised system.
donnyg - Saturday, May 28, 2011 - link
As SmithJ mentioned, a i7 computer with PCIe 16x/4x is only around $750 USD and that's including a GPU.You can easily get 2x HD6950x/6970s which do much better in that resolution anyway because of the VRAM requirements.
KoolAidMan1 - Sunday, May 29, 2011 - link
Throw in the same 2560x1440 IPS display and you're adding at least another $1000 to the whole package. Then there's operating system and the bundled software, and the fact that all-in-ones from any PC builder costs more than a standard ATX based PC.Given everything involved, the iMacs are actually a pretty good deal. Really fast, amazing display, tiny footprint, and silent. I still build my own PCs and I'll never give that up, but I love having it plugged into my iMac as a display and using both.
smithj - Saturday, May 28, 2011 - link
My shop runs iMacs because they're just so good with size and noise - we're really damned pleased that we've ditched the old noisy workstations and they're fast enough for what we want to do!But he's kind of right. For a consumer, iMacs aren't the best of value. A small mATX computer with an i7 2600 (what 99% of people going to do with an i7 I don't know) and an AMD HD 5850 only costs around $700, and this isn't even looking around. Throw in a 27" Ultrasharp or ACD and your whole computer is going to cost only $1500-1700.
They're popular because they're:
- Small
- Amazing looking
- Perform well enough
- Quiet
- Covered by the best consumer warranty in the market
- Good out of the box, no extra work required
Its got nothing to go with specs, most people who buy them frankly don't care about the specs. $500-700 extra to pay for a generally weaker computer is a bit annoying but I'm getting old and frankly the warranty service, ease of use, and lack of noise is loved by all.
smithj - Saturday, May 28, 2011 - link
We can't edit post. The point I'm making is that in a price/spec game, the iMacs are nowhere near as good as DIY PCs but there are some things that can't be directly put in a small HTML table.Apple to this day seems to be one of the few companies, if not the only, who understands this important factor.