The 27-inch Apple iMac Review (2011)
by Anand Lal Shimpi on May 27, 2011 2:30 AM ESTPower, Thermals and Noise
I started this review complaining about how loud the 15-inch MacBook Pro gets, but with 32x the physical volume the 27-inch iMac is near silent. Even under load the system is very quiet, almost too quiet. Apple chose a very lax fan profile which results in some very high external temperatures. The iMac takes in cool air from the bottom of the display and exhausts it up top behind the display. Playing Half Life 2 Episode Two I measured a maximum surface temperature of 125F at the exhaust vent. Again, unless you're doing something weird with the iMac on your lap this isn't an issue. Keep in mind that the Sandy Bridge CPU in the 15-inch MacBook Pro carries a 45W TDP and what's in the iMac is either 65W or 95W. Add in a larger, hotter hard drive and potentially a beefier GPU and you have a recipe for a pretty warm machine.
| 2011 iMac Power Usage | ||||||
| 27-inch iMac (Mid 2011) | Idle | Cinebench R11.5 | Half Life 2 Episode Two | |||
| Minimum Brightness | 54.1W | 108.3W | 149.0W | |||
| 50% Brightness | 86.6W | 141.6W | 180.0W | |||
| 100% Brightness | 144.5W | 198.3W | 240.0W | |||
With a large integrated display power consumption obviously varies depending on brightness. At idle, power consumption ranges from 54W to 144W. Under load the range quickly gets ever higher. I measured max system power consumption at 240W running Half Life 2 Episode Two.
Power consumption isn't out of control but you've got a billion transistor CPU, a 1.7B transistor GPU and a high resolution 27-inch display + backlight - it's going to draw some power.
Performance
Having never previously been a fan of the iMac, I don't actually have any historical performance data to compare to. What I do have however are scores from Mac Pros and of course the MacBook/MacBook Pro lines from the past couple of years.
Adobe Photoshop CS4 Performance
The Retouch Artists Speed Test we use for our CPU testing under Windows also works under OS X. We're running the exact same benchmark here, basically performing a bunch of image manipulations and filters and timing the entire process.
The high-end 27-inch iMac is a very capable Photoshop machine. A hair faster than the new MacBook Pro, the iMac delivers the same performance as an 8-core Mac Pro from 2009 or 2010.
Aperture 2 RAW Import
For my Aperture test I simply timed how long it took to import 203 12MP RAW images into the library.
We have a new winner here! The MacBook Pros were always limited by their slower 2.5" hard drive, but the iMac with Sandy Bridge in additional to a speedier disk give us better image import performance than the '09 and '10 Mac Pros. I told you this thing was fast.
Cinebench R10 & 11.5
I’m a fan of the Cinebench tests because they lets me show off both single and multithreaded performance in the same workload. First, the single threaded performance:
Sandy Bridge quad-core CPUs make no sacrifices. You get excellent single threaded performance which means general OS usage, launching applications and even rendering most web pages happens as fast as physically possible as the other cores are power gated and asleep. Start multitasking however and you'll see the Core i5 in this machine is no slouch:
There's still no replacement for more cores when it comes to heavily threaded applications, the past three years of 8-core Mac Pros are still faster than the new 27-inch iMac here. I suspect the upgraded Core i7 would at least let the iMac beat the 2008 Mac Pro thanks to Hyper Threading, but the other two systems are simply out of reach. For those users, you're better off waiting for the Sandy Bridge-E Mac Pro update expected sometime in Q4.
You'll notice in Cinebench R10 the 15-inch MacBook Pro is nipping at the heels of the new iMac. Chalk that up to the larger L3 cache and Hyper Threading, both advantages enjoyed by the MacBook Pro. Look at what those advantages do in Cinebench R11.5's multithreaded test:
Here the MacBook Pro actually gains on the iMac. More threads and more cache are better suited for the Cinebench workload. If you do a lot of offline 3D rendering and you want the iMac, I'd suggest upgrading to the Core i7-2600 that Apple offers. You get a not insignificant boost in clock speed but more importantly, Intel switches on Hyper Threading which gives you twice as many threads.
Quicktime H.264 Video Encoding
Our final benchmark is more consumer focused. Here I'm taking an XviD and converting it to an iPhone-supported H.264 format.
QuickTime doesn't make tremendous use of all cores all of the time, and thus the MacBook Pro loses its threading advantage. The iMac is our new champion of this test.
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Exodite - Friday, May 27, 2011 - link
Of course they are, I don't care the slightest about color fidelity or 178 degree viewing angles.The way I prefer to set up my displays will undoubtedly destroy and form of color calibration anyway.
KoolAidMan1 - Friday, May 27, 2011 - link
I hate TN panels, they're horrible. You're fortunate in that you don't care how things look, it is definitely cheaper.Exodite - Friday, May 27, 2011 - link
Strictly speaking I do care about how things look, I just don't consider IPS technology necessarily better for me personally.Being more prone to ghosting, and far more expensive, is far more a drawback than the better color fidelity, gamut and viewing angles are advantages. Again, for me personally.
Unfortunately there are no post-1080P displays targeted at anyone but the graphics professional. It's not just the panel technologies that are more expensive either, 27" - 30" displays tend to incorporate USB hubs, chargers, elaborate stands and exotic connectivity options that are all equally useless for me.
I'd love to see a minimalistic, matte, 2560x1440/1600 TN display with reasonable pricing.
Well, I wouldn't mind a IPS, PVA or other type of panel either if those end up more reasonably priced. I just don't particularly care about the advantages.
Then again I'm the guy that can't easily spot pentile matrix patterns or see any point in high-fidelity audio.
So I suppose you're right, I'm probably blessed - or at least my wallet thinks so. :)
KoolAidMan1 - Friday, May 27, 2011 - link
Vertical viewing angles are narrow enough and corner-to-corner uniformity is uneven enough to begin with on 23" monitors and the bulk of 13" laptop displays.A TN panel on a 27" would make these limitations even more apparent. I think you'd be happier with a higher number of smaller TN panels, as you're doing now. Even if the deficiencies don't bother you, there is a point where increasing size makes them even more obvious. When only a 30% band of the display looks anything close to uniform at any one time, I reckon that would bug nearly anybody. :)
Cheers
Exodite - Saturday, May 28, 2011 - link
You'd be surprised I suspect, as I can turn the second display quite a bit away before it gets to the point where it matters.There are quite a few 27" TN panels on the market already, though only 1080P ones so far, and they do sell so it can't be that bad.
I'm very happy with my two 19" 1280x1024 displays though, I just wish we'd see more progress in that area.
I got the displays in 2006, IIRC, and the push for 1920x1200 were going well... and then 1080P came into the picture and the whole market regressed to that and haven't budged since.
xSauronx - Friday, May 27, 2011 - link
Did you even read the article?" is the experience with having 2560x1440 resolution over 1920x1080 better then the experience that you get with $1600 worth of hardware over $700? I think I would say No."
You might, but Anand actually mentioned that he prefers one large monitor over two smaller ones with lower resolutions.
Id be tempted to agree, but 2 1080p monitors fit into my budget easier than did a 27 or 30" with high resolution.
/moneys, oh moneys. \
//mostly happy with these two guys, so oh well
kuk - Friday, May 27, 2011 - link
It's possible to use only the 27" display hooked to another computer (look for target display mode), though there still the space and power penalties, as the whole iMac system has to be running.KoolAidMan1 - Friday, May 27, 2011 - link
I addressed Target Display Mode in my post below. The Thunderbolt port has changed the requirements for TDM, now you need a Thunderbolt equipped computer to use it as a video source. For the time being the only computers you can use as a secondary source for the iMac display are other 2011 Macs equipped with Thunderbolt.I wasn't planning on replacing my current (non-Thunderbolt) 27" iMac, but this more than sealed the deal. Aside from being a Mac, my iMac also functions as the primary display for my gaming PC. The new iMacs are a step backward in this regard, at least until Thunderbolt ports show up in more computers next year or someone releases an adapter.
tipoo - Friday, May 27, 2011 - link
Ah, interesting. That's quite a step backwards IMO. You could always get switcher boards I guess, but that's added cost and not very elegant. And there's no guarantee that even Mac's in 2-4 years will use the same thunderbolt cable.Is it possible to go HDMI-Thunderbolt, say for a console or future laptop?
tipoo - Friday, May 27, 2011 - link
Also I've looked this up and someone on the Apple support forums said only the 15 and 17 inch MBP's could drive the iMac's display, is that true? The thunderbolt equipped 13 inch and MBA can't?