21.5-inch iMac (Late 2013) Review: Iris Pro Driving an Accurate Display
by Anand Lal Shimpi on October 7, 2013 3:28 AM ESTWiFi & IO
The new iMacs join the 2013 MacBook Airs in supporting 802.11ac. Unlike the MBA implementation however, the iMac features a 3 antenna/3 stream configuration with the potential for even higher performance. Connected to Apple’s new 802.11ac Airport Extreme I was able to negotiate the maximum link rate of 1300Mbps. I will say that maintaining the full speed connection was quite tricky and required very close proximity to the AP, and that the AP was located physically higher than the iMac.
Range was absolutely incredible on the Airport Extreme/2013 iMac combination. I didn’t have time to map out speed vs. distance from AP before leaving on my most recent trip, but I will say that the combination of the two gave me better WiFi range/performance than any other wireless device I’ve ever tested. I need to spend some more time with the two but color me completely impressed at this point.
With OS X 10.8.5 Apple addressed some of the performance issues that plagued real world use of 802.11ac. Prior to the 10.8.5 update,I could get great performance using iPerf, but actually copying files between Macs on the same network never substantially exceeded the performance I could get over 802.11n.
The 10.8.5 update somewhat addressed the problem, raising average performance copying over an AFP share to ~330Mbps. It’s not unusual for software companies to only partially address an issue in existing software, especially if there’s an actual fix coming just around the corner. I had a suspicion that’s what was going on here so I threw OS X 10.9 (Mavericks) on both the iMac and my source machine, a 13-inch MacBook Pro with Retina Display.
The 13-inch rMBP was connected over Thunderbolt/GigE, while the iMac was connected over 802.11ac to the same network. First, let’s look at UDP and TCP performance using iPerf:
Peak UDP performance is 829.8Mbps. Running the same test using TCP drops performance down to 553Mbps. What about actual file copy performance? I saw peak performance as high as 720Mbps, but average file copy speed over my network setup was ~500Mbps.
You can definitely get better transfer speeds over wired Gigabit Ethernet, but 802.11ac (particularly over short distances) is very good. You’ll need to wait for Mavericks to really enjoy this performance, but the wait is almost over.
The rest of the IO is the same as in last year's model. You get four USB 3.0 ports, two Thunderbolt 1.0 ports, GigE, SD card reader, and a 1/8" jack:
The Chassis
Last year Apple redesigned the iMac, making it thinner at the edges than an iPhone 5/5s or even an iPad mini. Many pointed out that reducing edge thickness didn’t really matter all that much given the center of the iMac bulges out quite a bit. Given that there’s no internal battery you need more space for, reducing chassis volume is purely an exercise in design with no real tradeoffs as long as you can adequately cool what’s inside. I can’t speak to the 21.5-inch iMacs with discrete graphics, but the 65W Haswell + Crystalwell model I was sampled exhibited no thermal issues during even heavy use.
The iMac’s lone internal fan hummed along at ~1400 RPM during light use as well as during repeated Cinebench R15 runs while writing this review. One positive side effect of Intel targeting notebooks for all of its microprocessor architectures is the ease of cooling these 65W “desktop” parts. Keep in mind that Apple delivers a similar amount of performance in a very thin 15-inch notebook chassis as it does in a 21.5-inch iMac chassis.
Despite the reduction in internal volume, the redesigned 27-inch iMac is still a bit bulky to move around. The same can’t be said for the 21.5-inch model however. Weighing only 12 pounds (the equivalent of a small dog or large cat), the 21.5-inch iMac is almost portable. I had to carry it around a lot during the course of my review (between desks, photo area, and in testing WiFi) and I quickly appreciated just how compact this system is. Particularly in its default configuration, there’s only a single cable you have to deal with: the carefully angled power cable going into the machine.
It’s also neat to look at the iMac compared to one of my 24-inch CPU testbed monitors from a few years ago and realize that the two have virtually the same resolution, and the iMac is not only a better display but comes with an integrated Haswell PC as well.
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elian123 - Monday, October 7, 2013 - link
Anand, could you perhaps indicate when you would expect higher-res iMac displays (as well as pc displays in general, not only all-in-ones)?solipsism - Monday, October 7, 2013 - link
Before that happens Apple will likely need to get their stand-alone Apple display "high-res". I don't expect it to go 2x like avery other one of their display; instead I would suspect it to be 4K, which is exactly 1.5x over the current 27" display size. Note that Apple mentioned 4K many times when previewing the Mac Pro.Also, the most common size for quality 4K panels appears to be 31.5" so I would't be surprised to see it move to that size. When the iMacs are to get updated I think each would then most likely use a slightly larger display panel.
mavere - Monday, October 7, 2013 - link
~75% of the stock desktop wallpapers in OSX 10.9 are at 5120x2880.It's probably the biggest nudge-nudge-wink-wink Apple has ever given for unannounced products.
name99 - Monday, October 7, 2013 - link
Why does Apple have to go to exactly 4K? We all understand the point, and the value, of going to 2x resolution. The only value in going to exactly 4K is cheaper screens (but cheaper screens means crappy lousy looking screens, so Apple doesn't care).jasonelmore - Monday, October 7, 2013 - link
4k is 16:9 ratio, to do a 16:10 right, they would have to do 5krepoman27 - Monday, October 7, 2013 - link
iMacs have been 16:9 since 2009, and 3840x2400 (4K 16:10) panels have been produced in the past and work just fine.repoman27 - Monday, October 7, 2013 - link
Apple is pretty locked in to the current screen sizes and 16:9 aspect ratio by the ID, and I can only imagine they will stick with the status quo for at least one more generation in order to recoup some of their obviously considerable design costs there.Since Apple sells at best a couple million iMacs of each form factor in a year’s time, they kinda have to source panels for which there are other interested customers—we’re not even close to iPhone or iPad numbers here. Thus I’d reckon we’ll see whatever panels they intend to use in future generations in the wild before those updates happen. As solipsism points out, the speculation that there will be a new ATD with a 31.5”, 3840x2160 panel released alongside the new Mac Pro makes total sense because other vendors are already shipping similar displays.
I actually made a chart to illustrate why a Retina iMac was unlikely anytime soon: http://i.imgur.com/CfYO008.png
I listed the size and resolution of previous LCD iMacs, as well as possible higher resolutions at 21.5” and 27”. Configurations that truly qualify as "Retina" are highlighted in green, and it looks as though pixel doubling will be Apple’s strategy when they make that move. I also highlighted configurations that require two DP 1.1a links or a DP 1.2 link in yellow, and those that demand four DP 1.1a links or two DP 1.2 links in red for both standard CVT and CVT with reduced blanking. Considering Apple has yet to ship any display that requires more than a single DP 1.1a link, and all of the Retina options at 27" are in the red is probably reason alone that such a device doesn't exist yet.
I also included the ASUS PQ321Q 31.5" 3840x2160 display, and the Retina MacBook Pros as points of comparison to illustrate the pricing issues that Retina iMacs would face. While there are affordable GPU options that could drive these displays and still maintain a reasonable degree of UI smoothness, the panels themselves either don't exist or would be prohibitively expensive for an iMac.
name99 - Monday, October 7, 2013 - link
OR what you chart tells us is that these devices will be early adopters of the mythical (but on its way) DisplayPort 1.3?Isn't it obvious that part of the slew of technologies to arrive when 4K hits the mainstream (as opposed to its current "we expect you to pay handsomely for something that is painful to use" phase will be an updated DisplayPort spec?
repoman27 - Monday, October 7, 2013 - link
Unlike HDMI 1.4, DisplayPort 1.2 can handle 4K just fine. I'd imagine DP 1.3 should take us to 8K.What baffles me is that every Mac Apple has shipped thus far with Thunderbolt and either a discrete GPU or Haswell has been DP 1.2 capable, but the ports are limited to DP 1.1a by the Thunderbolt controller. So even though Intel is supposedly shipping Redwood Ridge which has a DP 1.2 redriver, and Falcon Ridge which fully supports DP 1.2, we seem to be getting three generations of Macs where only the Mac Pros can actually output a DP 1.2 signal.
Furthermore, I don't know of any panels out there that actually support eDP HBR2 signaling (introduced in the eDP 1.2 specification in May 2010, clarified in eDP 1.3 in February 2011, and still going strong in eDP 1.4 as of January this year). The current crop of 4K displays appear to be driven by converting a DisplayPort 1.2 HBR2 signal that uses MST to treat the display as 2 separate regions into a ridiculously wide 8 channel LVDS signal. Basically, for now, driving a display at more than 2880x1800 seems to require multiple outputs from the GPU.
And to answer your question about why 4K, the problem is really more to do with creating a panel that has a pixel pitch somewhere in the no man's land between 150 and 190 PPI. Apple does a lot of work to make scaling decent even with straight up pixel doubling, but the in-between pixel densities would be really tricky, and probably not huge sellers in the Windows market. Apple needs help with volume in this case, they can't go it alone and expect anything short of ludicrously expensive.
name99 - Tuesday, October 8, 2013 - link
My bad. I had in mind the fancier forms of 4K like 10 bits (just possible) and 12 bit (not possible) at 60Hz, or 8bit at 120Hz; not your basic 8 bits at 60Hz. I should have filled in my reasoning.