CPU Analysis

The biggest part of Apple's Mac Pro announcement is of course the move to Intel processors and as many had predicted, Apple chose to go with Intel's Woodcrest based Xeon processors instead of Core 2 for the Mac Pro. Architecturally, the Woodcrest based Xeons are no different than the Conroe based Core 2 processors, so you get the same level of performance we showcased in our Core 2 review. With Xeon you do get the ability to go to multi-socket systems and a faster FSB, both of which are not possible with Core 2. Note that the Woodcrest based Xeons use a 771-pin LGA socket that is different than the 775-pin LGA socket used by the desktop Core 2 processors, so you can't swap them if you wanted to.

One of our biggest fears with Apple's use of Xeon instead of Core 2 is that it would put pricing of the Mac Pro above and beyond reasonable, but consulting Intel's price list left us pleasantly surprised:

 
Core 2
Clock/Cache/FSB
Price
Xeon
Clock/Cache/FSB
Price

X6800

2.93GHz/4M/1066

$999

5160

3.00GHz/4M/1333

$851

E6700

2.66GHz/4M/1066

$530

5150

2.66GHz/4M/1333

$690

E6600
2.40GHz/4M/1066
$316
5140
2.33GHz/4M/1333
$455
E6400
2.13GHz/2M/1066
$224
5130
2.00GHz/4M/1333
$316
E6300
1.86GHz/2M/1066
$183
5120
1.86GHz/4M/1066
$256
5110
1.60GHz/4M/1066
$209

Believe it or not, Intel's Xeon 5160, a faster alternative to the Core 2 Extreme X6800 is actually priced lower. At the very high end, from a purely processor standpoint, it makes sense for Apple to opt for the Xeon over the desktop Core 2 route because it's cheaper. It's not often that you see server/workstation processors priced lower than their desktop counterparts, so Core 2 Extreme owners should feel a bit ripped off (but the excellent performance can definitely numb the pain).

The Xeon 5160 aside, you're basically paying a premium for going with a Xeon over a Core 2, despite the fact that most of the time all you're getting is a faster FSB. While the 1333MHz FSB will do something, in the case of the Xeon 5150 vs. the Core 2 Duo E6700, you're paying 30% more for that advantage. Compared to the E6400, the Xeon 5130 costs 40% more and is clocked lower, although it has a larger L2 cache.

If you want to put Apple's performance in perspective, the slowest Mac Pro you can get is outfitted with a pair of Xeon 5130s. In single threaded applications, we'd expect the system to perform similarly to a Core 2 Duo E6400 system. In well multi-threaded applications, you'd be looking at significantly higher performance (dual dual core vs. single dual core).

The Xeon 5150 will obviously be a bit faster than the equivalently clocked Core 2 Duo E6700, thanks to the faster FSB. As we saw in our Core 2 review, in most Windows desktop applications we saw a 0 - 7.5% increase in performance, with the average increase being 2.3% due to the faster FSB. Multithreaded applications won't necessarily take better advantage of the faster FSB, it really depends on the application itself.

And obviously the Xeon 5160 will be faster than the current fastest desktop processor, Intel's Core 2 Extreme X6800. The performance advantage won't be tremendous, but it will be there.

If we were simply looking at single CPU configurations, Apple's decision to choose Woodcrest/Xeon over Conroe/Core 2 would have been an effort to keep average selling prices high, but none of the Mac Pros are single socket systems. Instead, Apple made an expensive but important move with the Mac Pros; by choosing Xeon, Apple can implement two sockets on the motherboard, which today means you can execute four simultaneous threads (dual dual core). By the end of this year, Intel will be shipping Clovertown, a quad core version of the dual core Xeons you see in today's Mac Pros. If Apple chooses to, with minimal effort, it could release 8-core Mac Pro systems in a matter of months (assuming Intel keeps its accelerated CPU schedule).

With four cores on a single die, the faster FSB matters that much more, so the 0 - 7.5% increase due to the 1333MHz FSB that we saw in our Core 2 review will go up. Seeing as how we were playing with quad core Kentsfield processors back in late May/early June, you had better believe that Apple designed its Mac Pro motherboards with support for Clovertown. While Apple isn't really touting processor upgradability with the new Mac Pro, it wouldn't be too far fetched to think that you could swap a pair of Clovertowns in these systems with no more than a firmware update.

Index The Chipset
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  • mesyn191 - Wednesday, August 9, 2006 - link

    They already said it was a supply and not a performance issue that made them go with Intel... Reply
  • hmurchison - Thursday, August 10, 2006 - link

    IBM wanting more money to develop the PPC 970 didn't help either. Moving to Intel was good. Reply
  • michael2k - Wednesday, August 9, 2006 - link

    Why not?

    The only thing closed about the Mac Pro is the motherboard; every other component can be replaced (CPU via socket, memory via sticks, video cards via PCIe, HDD via SATA, ODD via IDE), and the thing boots Mac OS X, Windows XP, and Linux.
    Reply

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