Intel's 8-core Skulltrail Platform: Close to Perfecting the Niche
by Anand Lal Shimpi on February 4, 2008 5:00 AM EST- Posted in
- CPUs
The CPUs
Late last year Intel announced the Core 2 Extreme QX9770, a 3.2GHz, 1.6GHz FSB quad-core desktop processor. We'll finally see availability of that beast this quarter, but you'll notice that the Skulltrail platform uses a slightly different CPU: the Core 2 Extreme QX9775. The 5 indicates that unlike the QX9770, this chip works in a LGA-771 socket just like Intel's Xeon processor. The different pinout is necessary because only Xeon chipsets support multiple CPU sockets and for a handful of reasons, that means we're limited to LGA-771.
LGA-771 QX9775 (left), LGA-775 QX9770 (right) - Can you spot the four missing pins?
The specs on the QX9775 are otherwise identical to its LGA-775 counterpart. The 45nm Yorkfield/Penryn core runs all four of its cores at 3.2GHz and is fed by a 1.6GHz FSB. Each pair of cores on the CPU package has a 6MB L2 cache, for 12MB total on each individual CPU.
Despite using a Xeon socket, the Core 2 Extreme QX9775 isn't a Xeon. It turns out there are some very subtle differences between Core 2 and Xeon processors, even if they're based on the same core. Intel tunes the prefetchers on Xeon and Core 2 CPUs differently so unlike the Xeon 5365 used in its V8 platform, the QX9775 is identical in every way to desktop Core 2 processors - the only difference being pinout.
Intel wouldn't give us any more information on how the prefetchers are different, but we suspect the algorithms are tuned according to the typical applications Xeons find themselves running vs. where most Core 2s end up.
Like all other Extreme edition processors, the QX9775 ships completely unlocked, making overclocking unbelievably easy as you'll soon see.
Cooling the beast, if you think those fins will cut you...they will.
The price point is going to be the worst part of the QX9775. Intel isn't publicly announcing the price per processor, but over $1000 is a starting point. It looks like QX9770s preorders are going for over $1500 so we'd expect the QX9775s to be priced similarly, possibly eventually settling at $1200.
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moiettoi - Friday, June 27, 2008 - link
Hi allThis sounds like a great board and for some-one like me that uses 4x22"monitors and does heaps of multi tasking it sounds perfect and would gladly pay the price asked.
BUT why is such a great board slowed right down by not having DDR3 memory sticks,,,because from what I've read at the momment there is not that much difference with running this and what I have now which is a quad core with DDR3 which runs great but I do overwork it.So bigger would be better.
You would think and I'm sure they already know that it would be common sence to make this board with DDR3 as it is it's only fault as far as I can see.
We will probably see that board come out soon or next in line once they have sold enough of these to satify there egos.
Great board but,,,,just not yet I will be waiting for the next one out which will have to carry DDR3,,,if they want to go forward in thier technolagy.
hnolagy
VooDooAddict - Thursday, February 7, 2008 - link
For testers of large distributed systems this is an awesome thing to have sitting on your desk.You can have a small server room running on one of these.
The biggest shortfall I see is cramming enough RAM on it.
iSOBigD - Tuesday, February 5, 2008 - link
I'm actually very disappointed with 3D rendering speed. Going from 1 core to 4 cores takes my rendering performance up by close to 400% (16 seconds to 4.something seconds, etc.) in Max with any renderer. (I've tried Scanline, MentalRay and VRay) ...so I'm surprised that going from 4 to 8 gives you 40-60% more speed. That's pretty pathetic, so I suspect the board is to blame, not the software.martin4wn - Tuesday, February 5, 2008 - link
Actually 40-60% is not disappointing at all, it's quite impressive. You are encountering the realities of Amdahl's law, which is that only the parallel part of the app scales. Here's a simple workthrough:Say the application is 94% parallel code and 6% serial. As you add cores, say the parallel part scales perfectly, so doubles in speed with every doubling in core count. Now say the runtime on one core is 16 seconds (your example). Of that, 1 second is serial code and the other 15 seconds is parallel code running serially.
Now running on a 4 core machine, you still have the 1s serial, but the parallel part drops to 15/4 = 3.75 seconds. Total runtime 4.75s. Overall scaling is 3.4x. Now go to 8 cores. Total runtime = 1 + 15/8 = 2.87s. Scaling of 60% going from 4 cores to 8 cores, and overall scaling of 5.5x
So the numbers are actually consistent with what you are seeing. It's a great illustration of the power of Amdahls law - even an app that is 94% parallel still only gains 60% going from 4 to 8 cores even with perfect scaling, and it's really hard to get good scaling at even moderate core counts. Once you get to 16 or more cores, expect scaling to fall off even more dramatically.
ChronoReverse - Tuesday, February 5, 2008 - link
This is why I'm quite happy with my quad core. What would probably be the useful limit on the desktop would be a quad core with SMT. After that faster individual cores will be needed regardless of how parallel our code gets (face it, you're not getting 90% parallelizeable software most of the time and even then 8 cores over 4 isn't getting more than about 50% boost in the best case for 90% parallel code).FullHiSpeed - Tuesday, February 5, 2008 - link
Why the heck does this D5400XS MB support only the QX9775 CPU ??? If you need to use 8 cores you can get a lot more bang for the buck with quad core Xeon 5400 series, with only 80 watts TDP each, up to 3 ghz. For a TOTAL of $508 ($254 each quad ) you can have 8 cores @ 2 Ghz.Last month I built a system with a Supermicro X7DWA-N MB ($500) and 4 gig of DDR2 667 ($220) and a single 2.83 Ghz Xeon E5440 ($773) , which I use to test Gen 2 PCIE, dual channel 8 Gb/s Fibre Channel boards, two boards at once.
Starglider - Tuesday, February 5, 2008 - link
Damnit. AMD could've destroyed this if they'd gotten their act togther. Tyan makes a 4 socket Opteron board that fits into an E-ATX form factor;http://www.tyan.com/product_board_detail.aspx?pid=...">http://www.tyan.com/product_board_detail.aspx?pid=...
I was strongly tempted to get one before the whole Barcelona launch farce. If AMD hadn't made such horrible execution blunders and could have devoted the kind of resources Intel had to a project like this, we could have four Barcelonas running at 3 to 3.6 GHz with eight DDR2 slots all on a dedicated channel. Ah well. Guess I'll be waiting for Nehalem.
enigma1997 - Tuesday, February 5, 2008 - link
Note what Francois said in his Feb 04 reply re memory timing http://blogs.intel.com/technology/2008/01/skulltra...">http://blogs.intel.com/technology/2008/01/skulltra... Do you think it would help the latency and make it closer to DDR2/DDR3 ones? Thanks.enigma1997 - Tuesday, February 5, 2008 - link
CL3 FBDIMM from Kingston would be "insanely fast"?! Have a read of this artcile: http://www.tgdaily.com/content/view/34636/135/">http://www.tgdaily.com/content/view/34636/135/Visual - Tuesday, February 5, 2008 - link
I must say, I am very disappointed.Not from performance - everything is as expected on this front... I didn't even need to see benchmarks about it.
But prices and availability are hell. AMD giving up on QuadFX is hell. Intel not letting us use DDR2 is hell.
I was really hoping I could get a dual-socket board with a couple (or quad) PCI-express x16 slots and standard ram, coupled with a pair of relatively inexpensive quadcore CPUs. Why is that too much to ask?
The ASUS L1N64-SLI WS board has been available for an eon now, costs less than $300 and has quite a good feature set. Quadcore Opterons for the same socket are also available for more than a quarter, some models as cheap as $200-$250.
Unfortunately, for some god-damned reason neither ASUS not AMD are willing to make this board work with these CPUs. The board works just fine with dual-core Opterons, all the while using standard unbuffered unregistered DDR2 modules, but not with quad cores? WTF.
And that board is old like the world now. I am quite certain AMD could, if they wanted, have a refresh already - using the newest and coolest chipsets with PCIe 2.0, HT 3.0, independent power planes for each cpu, etc.
Intel could also certainly have a dual socket board that works with cheap DDR2, have plenty PCI-express slots, and the cheap $300 quad-core Xeons that are out already instead of the $1500 "extremes".
I feel like the industry is purposely slowing, throttling technological progress. It's like AMD and Intel just don't want to give us the maximum of their real capabilities, because that would devalue their existing products too quickly. They are just standing around idly most of the time, trying to sell out their old tech.
Same as nVidia not letting us have SLI on all boards, or ATI not allowing crossfire on nforce for that matter.
Same as a whole lot of other manufacturers too...
I feel like there is some huge anti-progress conspiracy going on.