Weeks have passed since Apple's announcement of the Mac Pro, and while we wanted to conclude our look at the Mac Pro much earlier, like many Mac Pro users we ran into some serious performance issues under Windows XP.

With the Mac Pro performance issues resolved and some more time with the system under our belts, we're able to bring you the final part in our Mac Pro coverage. This time we're focusing on upgrading the memory and CPUs in the Mac Pro, as well as looking at its performance as a PC running Windows XP.

As a high end Xeon based machine that can run both Mac OS X and Windows XP, the Mac Pro has the potential to be the power user's dream. Today our task is to find out just how upgradable this machine is and how well it runs XP, if it can truly be your only system if you're a Mac and PC user.

FBD Revisited

Thus far the only real downside we've seen to the Mac Pro is its use of Fully Buffered DIMM (FBD). As we mentioned in our initial article discussing the Mac Pro's specifications, the FBD spec calls for a serial interface between memory controller and memory modules, while allowing the chips on the memory modules themselves to be regular mainstream DDR2 devices. A FBD memory controller talks to an AMB (Advanced Memory Buffer) on each memory module, which acts as a translation hub and buffer for all communication between the DDR2 devices on the module and the requests from the memory controller.

The major benefit of FBD is the ability to feature more memory modules per channel (up to 8 per channel), offering greater capacity for high end servers and workstations than even registered DDR2. The downside to FBD is that there is significant overhead and latency introduced by using a packetized interface and using the AMBs to translate from one interface technology to another (FBD to DDR2).

As we mentioned and proved in our previous articles, the number and configuration of FB-DIMMs in your Mac Pro can affect performance. The Intel 5000X chipset in the Mac Pro features two 144-bit FBD branches, each being the width of two FB-DIMMs (effectively giving the chipset four "channels"). Therefore you need at least two FB-DIMMs in the system (the width of a single FBD branch), but ideally you'd need at least four to have a hope of attaining peak bandwidth.

As some of our readers (and Intel) pointed out, the story doesn't just end at needing four FB-DIMMs. The rank of the FB-DIMMs can impact performance as well, and ideally each of your FB-DIMM modules would be dual rank modules. The rank of a DIMM is determined by dividing the width of all of the devices on the module by the width of the module itself. For example, a single rank FB-DIMM would have 9 DDR2 devices each being 8-bits wide. A dual rank FB-DIMM would be composed of 18 DDR2 devices, each still being 8-bits wide. All of our 512MB FB-DIMMs are single rank modules, while our 1GB and 2GB modules are dual rank.

The story doesn't end with rank though. Because of the dedicated read and write lanes between the memory controller and the AMBs on FB-DIMMs, you can be reading from one FB-DIMM while writing to another. So in theory, if you're running an application (or combination of applications) that have a lot of concurrent reads and writes going on you could stand to benefit from having more than one FB-DIMM per channel.

Based on all of the above information, it would seem like your best bet is to stick as many dual rank FB-DIMMs as you can afford in your system, and if that were the case then we'd be able to move on from here. Unfortunately it's not, because as we mentioned in previous articles, the more FB-DIMMs you have in your system, the higher access latencies will be to those additional FB-DIMMs.

What we then end up with is a tradeoff between more bandwidth and higher latency, so which route do you take? We've done a lot of testing and most of our tests seem to favor the four dual-rank FB-DIMM module configuration, but the number/configuration of modules really depends on your particular needs. We're still testing to figure out what the tangible real world performance differences are between the multitude of memory configurations, but for now just know that if you need maximum bandwidth you'll want 8 dual rank FB-DIMMs, but if you want lower latency you'll want fewer modules. Whether or not you'll see a performance difference will depend mostly on the application(s) you're running.

Third Party Memory Modules
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  • Calin - Tuesday, September 12, 2006 - link

    Assuming you want a workstation capable of accessing 16GB of RAM (and using two processors), your options are a bit more reduced. There was an article on Anandtech, and the Mac Pro (the most expensive) was just a couple of hundred dollars more expensive than the sum of its components (and operating system I think).
  • tuteja1986 - Tuesday, September 12, 2006 - link

    Intel Xeon 5150 2.66Ghz
    1GB PC2-5300 DDR2
    250GB 7200RPM Sata-II
    16x DVDRW
    Good Looking Case
    Server Mobo
    Mac OS



    Intel Xeon 5150 2.66Ghz $729
    3x 250GB Western Digital in raid 5 $65 each = $195
    Pionere 110D = $50
    7900GT $260
    2x 1GBx2 OCZ PC2-5300 $200 each = $400
    TYAN S5370G2NR-RS Dual Socket 771 Intel 5000V SSI CEB Server Motherboard $319 supports 16GB ram
    Cool Master Stacker $154
    Rosewill RP600V2-S-SL 600W SLI Ready $70
    Linux OS , Microsoft Windows XP Professional X64 Edition Single Pack $139


    I know what i will pick :!
  • grtgrfx - Monday, December 21, 2009 - link

    And which one will run cooler and be completely silent when you push it? Ah, the Mac will. High quality build, excellent components, superior GUI: $2,500. Peace and quiet while working: priceless.
  • Nimbo - Tuesday, September 12, 2006 - link

    Anand did compare prices in its second article about Mac pro
    Mac Pro: $2499
    Dell equivalent: $3110
    Home Built: $2390
  • tuteja1986 - Wednesday, September 13, 2006 - link

    MAC PRO $2499

    Two 2.66GHz Dual-Core Intel Xeon
    1GB (2 x 512MB)
    250GB 7200-rpm Serial ATA 3Gb/s
    NVIDIA GeForce 7300 GT 256MB (single-link DVI/dual-link DVI)
    One 16x SuperDrive
    Apple Keyboard and Mighty Mouse - U.S. English
    Mac OS X - U.S. English

    - not include :
    Server OSX
    Fiber Channel Cards
    Wireless Option
    Any Apple Software
    Or even Apple Care Protection Plan (APP)

    Now if your doing loads of Video Editing/encoding.. one Gigabyte ram is crap all and 1 250GB is to little...

    Two 2.66GHz Dual-Core Intel Xeon
    4GB (4 x 1GB)
    500GB 7200-rpm Serial ATA 3Gb/s
    500GB 7200-rpm Serial ATA 3Gb/s
    500GB 7200-rpm Serial ATA 3Gb/s
    ATI Radeon X1900 XT 512MB (2 x dual-link DVI)
    One 16x SuperDrive
    Apple Wireless Keyboard and Apple wireless Mighty Mouse - U.S. English
    Mac OS X - U.S. English

    - not include :
    Server OSX
    Fiber Channel Cards
    Wireless Option
    Any Apple Software
    Or even Apple Care Protection Plan (APP)

    At Mac Customize they don't give you a chose of additional 250GB hard drive just 500GB Hard drive

    Now Windows/Linux PC is where it shins :

    Intel Xeon 5150 Woodcrest $729 : $1458

    Western Digital Caviar SE16 WD5000KS 500GB 7200 RPM SATA 3.0Gb x3 $189 = $567

    HIS/Sapphire/Asus Radeon X1900XT 256MB GDDR3 PCI Express x16 CrossFire Video Card - $300-$320 could way more cheaper with rebate

    NEC/LG/Sony/Lite-on 16X DVD±R DVD Burner Beige IDE Model ND-3550A $30

    hermaltake Armor Series VA8000BWS Black Computer Case - Retail $149

    Rosewill RP600V2-S-SL 600W SLI Ready $70

    Logitech Cordless DesktopS Keyboard Mouse $58

    Creative Sound Blaster $40

    Windows XP PRO 64bit $139

    TYAN S5370G2NR-RS Dual Socket 771 Intel 5000V SSI CEB Server Motherboard $320

    Crucial Technology 1GB 240-Pin DDR2 FB-DIMM DDR2 667 $170 x 4 = $680


  • tech010101x - Wednesday, September 13, 2006 - link

    You do realize that the Mac Pro comes with all the drive sleds... you can add the WD5000KS drives yourself later. You can also add memory yourself.

    Doing it this way... ordering the Mac Pro with 2 x 512MB RAM and 1 500GB drive costs: $3009.
    Add in the RAM you quote: 4 DIMMS at $680 + 2 WD5000KS at $189 @ = $4067
    Total difference then is a mere $256.

    You are still missing firewire 400 and 800 and firewire target disk mode.
    The power supply in the Mac Pro is much beefier.
    Windows XP 64 bit is a mess.

    And then we get to the fact that you are comparing a retail price to a non-retail price, comparing a bunch of parts to a fully assembled system, and you are leaving out the shipping issue altogether. Certainly, it is possible to pay $4,909 + tax for the Mac Pro. It is also very possible to pay far less.

    The arguments in this regard are less about Apple and more about homebuilt vs. Tier 1 vendor. You might as well be comparing against IBM Intellistations, Sun Ultra 40's, or HP xw8400's. You'd appreciate it not being a homebuilt when you have to manage many of these over time.

    A 5% discount on the base system + the extra RAM and drives added later is $3917, or $106 difference. I usually get bigger discounts than that 5% on systems like this.

    In the end, if you aren't interested in using Mac OS X at all, the Mac Pro is probably not for you. It is the complete suite... from the hardware (including the nice boot menu, target disk mode, etc), the software (Mac OS X, iLife, platform user experience, etc.), solutions integration (Xsan costs $999 vs. ADIC StorNext at $4k for SAN filesystems), on through to applications (Final Cut Studio, Shake, etc.).
  • Calin - Wednesday, September 13, 2006 - link

    Windows XP Professional supports two processors (cores) out of the box. Put a Windows 2003, and see where you get...
  • Sunrise089 - Tuesday, September 12, 2006 - link

    and even that "home built" price was without a case, OS, or power supply.
  • Calin - Wednesday, September 13, 2006 - link

    As for the OS, you could "migrate" your Windows XP - with one small problem - XP is 1-2 processors only, this configuration would have 4 cores...
    So, add another ... for Windows 2003
  • JarredWalton - Wednesday, September 13, 2006 - link

    Sorry, but that's wrong. XP is 1-2 *sockets* only. XP home will work with a dual core or even quad core CPU just fine, and XP Pro works with all 2S workstation setups without difficulty. Microsoft modified the way they count CPUs when dual core first came out.

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