ATI Radeon HD 3870 & 3850: A Return to Competition
by Anand Lal Shimpi & Derek Wilson on November 15, 2007 12:00 AM EST- Posted in
- GPUs
2, 3 or 4 GPUs: Introducing CrossFire X
DirectX 9 didn't support more than 3 frame render ahead, and we saw this manifest in less than optimal scaling on NVIDIA's quad SLI solutions. Now that Vista and DirectX 10 are around, it's possible to render 4 or more frames ahead, and quad solutions have a higher potential. AMD is taking advantage of this via CrossFireX which currently enables up to 4 GPUs to be connected in the same system with three CrossFire bridges. It's not a pretty solution: you'll need a non NVIDIA chipset motherboard with 4 physical x16 PCIe slots.
Aside from potential performance scalability, there is also the capability to support up to 8 monitors from one system with 4 graphics cards installed. While this isn't as universally desired, it could be something fun to play with. We don't currently have a platform solution that we can use to test this yet, but we will certainly test this when we are able.
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Parhel - Thursday, November 15, 2007 - link
Even though you're wrong, do you mind if I use your math on my upcoming trip to Europe? It would really help me out. :)MrKaz - Thursday, November 15, 2007 - link
Since no one seems to ask but since when crossfire works on Nvidia 680i?Also you said this correctly over load power:
"The difference is negligible, but when you include the fact that the 8800 GT is faster, the Radeon HD 3870 actually has worse performance-per-watt than the competition. "
But you unfortunately failed to mention this over idle power:
"The difference is huge, especially when comparing to the older ATI and NVIDIA offers, even when comparing to the new 8800GT it’s still a 40 Watts difference."
Anand Lal Shimpi - Thursday, November 15, 2007 - link
It doesn't, we used a P965 board for CrossFire, but you couldn't have known that - thus I've updated the test table :)And I've included commentary on the idle power of the 3800 series, my apologies for the oversight.
Take care,
Anand
MrKaz - Thursday, November 15, 2007 - link
Anand do you think Crossfire scaling would improve if you used some X38 or rd580?Or the 4x PCIe slot on 965 doesn’t affect it much?
Does the 790 and Phenom get reviewed this month?
Continue the good work!
Anand Lal Shimpi - Thursday, November 15, 2007 - link
Personally I don't think the chipset is at fault for poor scaling here, but you do make a good point - I'll see if we can run some numbers internally and figure that out.Indeed this isn't the only AMD product that gets reviewed this month...
:)
Anand Lal Shimpi - Thursday, November 15, 2007 - link
Woops, my mistake, Derek ran the CF tests and they were on a P35 board and not a P965. I've updated the article accordingly.Take care,
Anand
MrKaz - Thursday, November 15, 2007 - link
Thanks Anand!jcromano - Thursday, November 15, 2007 - link
From page 5:I have been unable to use the RTPE for the past two weeks or so. What's the trick? Here is the error it gives me:
Jim
Crassus - Thursday, November 15, 2007 - link
Yep. Same here error message here, both in Firefox and IE. I've been trying to make use of the RTPE for weeks now, without success. Or was it converted to Anandtech "staff only" use? ;c)jcromano - Thursday, November 15, 2007 - link
Ok. Thanks for the quick response. I look forward to the return of the RTPE, but maybe your shopping page can substitute in the meantime.Cheers,
Jim