17" Apple iMac - The Official SPCR Review

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Testing on the iMac was quite simple in some ways, and very complex in others. Because it is a complete system, there were no drives to suspend or fans to tweak, so measuring noise was as simple as placing the sound meter one meter away and taking a reading.

Power and thermal testing, on the other hand, was complicated immensely because we are unfamiliar with any of the hardware monitoring and benchmarking tools available for OS X. And, for some reason none of the OS X-based utilities that we downloaded could detect any temperatures other than the SMART data from the hard drive. Because of these limitations, our stress testing consisted of running a custom-compiled version of CPUBurn for a long period of time and hoping that nothing crashed.

The ambient noise level at the time of testing was 17 [email protected]

iMac: OS X
Activity State
Noise Level
AC Power Draw
Low Power Idle
HDD Seek @ Idle
2 x CPUBurn

With a maximum power draw of 63W, the iMac certainly qualifies as a low power system. At idle, the system drew 46W, which will qualify for approval from EnergyStar if their current draft computer spec makes it to the planned 2007 release. Even better, the system falls back into a low power mode after being left alone for a few minutes, dropping the power even more to just 33W. By way of comparison, the lowest idle power consumption we've ever seen from a custom built system is 36W — and that doesn't include an LCD monitor.

Much of the power savings in the low power mode seems to come from a reduction in the brightness of the LCD screen, which drops to the lowest possible brightness. This sometimes got quite irritating, since the low power mode sometimes kicked in while reading a large block of text on a web page and the mouse would have to be moved around to boost the brightness back up. One solution might have been to turn the brightness down all the time, but this might not be practical in a brightly lit room.

If the system was left alone for much longer — about 15 minutes — the system would shut itself down into standby mode, where the total power consumption dropped to just two watts. Like the low power mode, this also had its drawbacks. In fact, it had a habit of shutting itself down while we were running CPUBurn, making it difficult to sustain the test for a long period of time.

The energy efficiency of the iMac solves the mystery of how it is able to get away with so little cooling. At first glance, the numbers don't look that impressive, but keep in mind that all of these numbers include the power required by the LCD screen. Stand-alone LCD monitors typically draw between 30~40W from the wall, so we were quite impressed when the entire system managed to draw this little power.

The noise levels were no less impressive than the power efficiency. At idle (that is, most of the time), the noise level was a paltry 20 [email protected], but even then the noise was barely distinguishable from the ambient noise in the lab. The noise character was very smooth, mostly a slight whirr masked by airflow that sounded like the hard drive. Although the iMac contains a full size 7,200 RPM drive, there was surprisingly little low frequency hum. The secret may be the metal stand, which seemed to absorb much of the vibration from the drive. The drive vibration could be clearly felt by placing a hand on the back panel, but a no vibration at all could be felt at the base of the stand.

Seek noise from the drive was plainly audible, and was the most annoying feature of the iMac's sonic character. It was much more audible than the measured difference suggests, primarily because the clicks did not fade easily into background. We did not get a chance to test whether AAM was enabled. If it was not, the issue of seek noise might become a non-issue.

Although the noise levels did rise slightly with CPUBurn running, the increase was almost imperceptible. In fact, if we hadn't measured the difference, we probably wouldn't have noticed — the noise character did not seem to change at all. Only the sudden realization that the iMac was easier to hear against the background noise convinced us that there was any audible difference at all.

iMac: Optical Drive Noise
Activity State
Noise Level
First spin-up
30s idle
1m idle

As is the case for almost any system, the optical drive was a significant source of noise when it was in use. At full speed, it measured 31 [email protected] — not quiet, but better than most full-sized drives. Subjectively, it also sounded a little bit nicer: It was smoother and sounded less mechanical. The bulk of the noise was a clean whirr floating on a bed of airflow noise, with very little low frequency hum. The better subjective quality can probably be attributed to the well-sealed slot, which didn't let much noise out, and to the thick plastic body of the iMac, which is much less prone to resonance than aluminum or steel.

Fortunately, the full blast noise level of the optical drive only lasted for about thirty seconds, even when the drive was in heavy use. After that, the noise level dropped to a respectable 24 [email protected], where it stayed while the drive was in use. Once the drive had stopped being accessed, the noise level dropped even further to 21 [email protected], where it was completely inaudible unless specifically listened for. When left idle for another ten minutes, the drive stopped spinning entirely.


Not a day after we completed our testing, Apple announced that their Intel-based systems would be supporting Windows XP via a firmware update known as Boot Camp. An update to OS X would also allow the default operating system to be selected and changed. This provided us with an excellent opportunity to run a test with our standard tools. We jumped at the chance in hopes of being able to access the thermal sensors.

The Mac side of the upgrade was quite painless. Step by step instructions guided us through the procedure of updating the firmware to emulate an 8088 BIOS, burning a Windows-compatible driver disc, updating OS X, creating a Windows partition, and then finally rebooting the system to begin the Windows installation process.

As usual, installing Windows was an overly long process, but it proceeded without any more troubles than usual. Care had to be taken to select the correct partition, but no other special procedures needed to be followed.

Once Windows was installed, the Apple-provided driver disc provided drivers for all of the essential hardware, but even with the drivers fully installed there were still a few unrecognized devices in the Device Manager.

Apple explicitly states that iSight (the webcam) and the Apple Remote (for HTPC functionality) are not supported under Windows XP, but a webcam did show up in the Control Panel under Scanners and Cameras. Double clicking on this icon immediately produced a Blue Screen of Death. Next time we'll listen to Apple, but it was entertaining to see an iMac with the Blue Screen of Death.

Something we never thought we'd see: The Apple and Windows logos side by side.

Alas, our hopes of being able to see the CPU temperature were in vain, as SpeedFan 4.28 did not detect any thermal sensors aside from SMART. Once again we were stymied. However, we did manage to run CPUBurn again and ATI Tool to stress the graphics subsystem. We also tried to run Throttlewatch, but once again we were unable to detect anything of use — it reported both versions of Intel's Thermal Management as being disabled.

iMac: Windows XP
Activity State
Noise Level
AC Power Draw
Idle (LCD Brightness @ Minimum)
Idle (LCD on standby)
2 x CPUBurn
2 x CPUBurn + ATI Tool

Surprisingly, power consumption was higher across the board when Windows was running. Only at idle was the difference small enough to ignore. With CPUBurn running, the power draw was three watts higher — quite shocking because the code should have been identical down to the instruction. CPUBurn is coded in x86 assembly, so there should have been no differences in the final code that was executed. Presumably, differences in the way OS X and Windows schedule the tasks are responsible for the differences.

We were able to push the power consumption even further when we ran ATI Tool alongside CPUBurn. The end result was a system, LCD included, that drew a total of 73W from the wall — an amazing result for a full CPU and GPU stress test. Even during this intensive test, the noise level never rose above what it was with only the CPU under stress.

Because Windows did not support the low power idle mode that was present in OS X, the idle power level never dropped quite as low as it did in OS X. Manually turning the LCD brightness down to minimum (via an Apple supplied tool in the system tray) dropped the power by ten watts, but even that was not enough to match the 33W level reached by OS X in low power mode. Clearly, OS X disables other features as well as dimming the LCD. In fact, even when the LCD was turned off entirely by tinkering with the Power Management settings, the power level was still above what OS X achieved with the LCD dimmed. Assuming that Apple's drivers allowed Windows full control over the motherboard, this seems to indicate that OS X is more effective at reducing system power — notebook users take note.


The 17" iMac has almost everything a silencer could want. It's quiet, efficient, good value (never thought we'd say that about an Apple), and it can even run Windows. It is also the only Core Duo-based "desktop" system currently available. We want one.

More than anything else, it was the ergonomics and design that impressed us about the iMac. Ordinarily, we rarely go for form over functionality, but, so long as you're willing to leave it alone without tinkering, the iMac is perfectly functional. It is difficult to quantify exactly how the iMac succeeds so well, as the difference is qualitative. The iMac has the feel of a luxury sedan, a Mercedes perhaps. Sure, a Lamborghini or a souped up Civic is more thrilling, but for sheer comfort and ease of use it's hard to beat the iMac.

The one exception is Apple's "Mighty Mouse". Although it pretends to have a scroll wheel and "two button" functionality, using the tiny, hypersensitive ball to scroll up and down was frustrating, and it took one of us the better part of an hour to master right clicking. The arrow movement is also too slow, even at maximum speed.

It's ironic that Apple would be the first company to take an Intel processor designed originally for mobile use and create such a compelling product. The question is whether any of the Windows/PC companies will come up with a viable competitor to the Core Duo iMac. Surely, there is a market for such a product!

Long story short, the iMac is a computer for the connoisseur and for "Everyman", just as Apple intended. Power users, enthusiasts, anyone who wants to tweak the hell out of everything should probably stick to building their own systems — they'll be happier molding the computer to their own personal quirks. However, for those who want to use a computer, not take up computer building as a hobby, the iMac is among the best there is.

Much thanks to Apple Canada for supplying the 17" iMac sample for us to review.


SPCR Articles of Related Interest

Apple iMac w/Intel Core Duo: A User's Review
Shuttle's Smallest Yet: XPC X100
Fanless Ultra Powerhouse PC by EndPCNoise

Eternal link: Kodawarisan's Photo Tour of Core Duo iMac

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