The Computer Blog

Tuesday, November 24, 2009

Is the iCore iMac Really a Mac Pro Replacement?

Whenever Apple releases a new batch of machines, they always publish a set of benchmarks demonstrating how much faster the newer systems are than the ones they replaced. That’s all well and good if you’re made of money and can afford to replace just bought systems with new ones. But the question that often becomes difficult to answer is how these new systems stack up against systems two or more generations back. By inference, we are to think they are faster without a doubt; but, as I’m going to show you here, that’s not always the case.

My curiosity about this became enflamed when the website released a graph comparing the new i5 and i7 powered iMacs against current generation Mac Pro’s. I own a late 2008 8-core (dual processor four core) Intel Xeon powered 5400 Mac Pro running 14 GB of RAM and an ATI Radeon 3870 video card. I wanted to know how it would stack up against the new i7 iMac. To find out, I borrowed Barefeats’ data and ran Cinebench 10 under Snow Leopard and Windows 7. While running a single benchmarking program never gives you the full story, Cinebench has been a consistent way to perform single or cross-platform comparisons for some time. That’s not to say it’s perfect, as some of the test results will later raise some questions about how optimized it is for current versions of OS X.

First, you can see the results at this page: Only the multi-processor (Cinebench) results are shown, but the 8 core Mac Pro, a 2.93GHz machine with 12GB of RAM and an ATI Radeon 4870 video card, comes in with a score of 25878. A four core version of the same machine comes in at 15521. The 4 core i7 iMac with a Radeon 4850 video card and 8 GB RAM comes in at a very close 15290, while the i5 iMac comes in at 12077. My 2.8 GHz 8 Core Xeon Mac Pro with 14 GB RAM an a Radeon 3870 video card came in at 18588 on the same test. The puts it below the 8 core 2.93 Ghz Mac Pro but above the i7 iMac. Based on that, from a performance perspective only, I would lose by moving to an i7 iMac, especially considering I can gain some more “oomph” by changing out my Radeon 3870 card for a 4870.

I haven’t seen or tried to look for benchmarks from a first generation four core 2.66 Mac Pro, but I suspect the current i7 iMac would give that machine a run for its money and perhaps even sneak past it.

All that said, if you’re really considering whether to go with an i7 iMac or a new Mac Pro, the picture gets a lot murkier once you step away from looking at performance alone. First, the new 27 inch iMacs have a display that’s second to none; I know of no other way to describe it than “absolutely stunning”. Secondly, with 1 TB and 2 TB options for hard disk storage (even if the 2 TB option is a bit pricey), you can order an iMac with lots of room, though admittedly a professional video shop might find even that space a bit confining. You can equip the new iMacs with up to 16GB of RAM, enough for a professional or semi-professional setting, though if you buy all that extra RAM from Apple you will probably break your piggy-bank. Moreover, you used to be able to buy a fully-equipped tower for $3000; but getting a top of the line Apple tower today will easily set you back $5000 or more. This cost escalation is further widening the line between consumer and “pro” machines to the point where Apple runs the risk of marginalizing itself too much and driving both semi-pro’s and pro’s to the Windows platform. Frankly, if something happens to my current Mac Pro and I choose not to repair it, I will be looking at an i7 iMac (or its replacement) rather than at a Mac Pro line for its replacement.

Now that we’ve discussed that, I’d like to discuss the Cinebench test results in more detail.

I’m running Mac OS X and Windows 7 64-bit, the latter under Boot Camp.

Operating System: Mac OS X 10.6.2, 32 bit
Single CPU Rendering: 3241
Multi-CPU Rendering: 18588
Speed Up Factor: 5.74
Open GL: 6446

Operating System: Mac OS 10.6.2, 64 bit
Single CPU Rendering: 3245
Multi-CPU Rendering: 18564
Speed Up Factor: 5.72

Operating System: Windows 7 Ultimate, 64 bit
Single CPU Rendering: 3435
Multi- CPU Rendering: 20277
Speed-Up Factor: 5.90
OpenGL: 6597

The numbers seem to indicate that Cinebench performs better under Windows 7 than under Snow Leopard, but I honestly can’t say that’s a justified conclusion. The Cinebench download included a separate 64 bit optimized Cinebench test for Windows but only one for OS X. Additionally, Cinenbench reported it was running in 32 bit OS X even though Apple’s System Information confirmed that the 64 bit kernel and extensions for Snow Leopard were loaded. Therefore, I don’t have enough information to say for sure that Windows 7 is faster, but it does appear that Apple STILL isn’t doing everything it can to optimize performance under OpenGL, and it’s been that way for some time.

For curiosity and completeness’s sake, I also ran Cinebench on my 15 inch Unibody MacBook Pro powered by a 2.4 GHz Core 2 Duo CPU running under 3 GB of RAM and with a Nvidia GeForce 9600M GPU. I ran Snow Leopard in both 32 bit and 64 bit modes.

Operating System: Mac OS 10.6.2, 32 bit
Single CPU Rendering: 2719
Multi-CPU Rendering: 4927
Speed-Up: 1.81
OpenGL: 4907
Operating System, Mac OS 10.6.2, 64 bit
Single CPU Rendering: 2725
Multi-CPU Rendering: 4908
Speed-Up: 1.80
Open GL: 4882

Once again, notice that 64 bit performance of multi-CPU rendering within Cinebench in Snow Leopard lags its 32 bit counterpart on two different machines with two different GPU’s. Again, that makes me question whether Cinebench really can take advantage of 64 bit functions in OS X, though the results are not so far apart from the Windows 7 results that a conclusion can be drawn either way.

The one thing that is clear, however, is that there is a huge performance difference between the i7 or i5 iMac and Apple’s current line of MacBook Pro laptops. If you’re performing tasks that require as much horsepower as you can afford, then you might want to consider moving to one of these iMacs rather than using your MacBook Pro as a desktop. If you need both a laptop and a desktop but can only afford one, then buying a MacBook Pro with an Apple 24 inch LED Cinema Display is certainly the way to go. (That’s how I’m operating though I use my Mac Pro to cover the performance gap as needed.) It all depends on how much Apple you can afford and how much sitting you’re willing to do.


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