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
Multi-GPU Scaling: Two 3850s = One 8800 GTX?
AMD only sent us a pair of Radeon HD 3850s for this review (believe it or not, we had to beg to get a single 3870), so our only CrossFire numbers come from this setup. That being said, the performance is quite respectable:
Believe it or not, but a pair of these $179 Radeon HD 3850s actually gives you the same performance as a single GeForce 8800 GTX.
| Multi-GPU Scaling (2560 x 1600) | Radeon HD 3850 CF | GeForce 8800 GT SLI |
| Oblivion | 1.7x | 1.87x |
| Unreal Tournament 3 | 1.48x | 1.66x |
Scaling looks pretty good from the Radeon HD 3850, however it's still not as good as what NVIDIA is able to achieve with the 8800 GT. NVIDIA consistently achieves about 11% better scaling from one to two GPUs than AMD.
The other problem with CrossFire is that it simply doesn't always work, so a pair of 3850s is not necessarily a better option than a single 8800 GT or GTX. Case in point would be the two other games that we wanted to include here: Quake Wars and Call of Duty 4, both gave us lower frame rates with CF enabled than without. AMD's release notes for the Radeon HD 3800 drivers informs us that some applications may show a performance decrease with CF enabled, so we're not too surprised.
While it'd be nice to be able to purchase two cheap cards and get better performance than the best out there, there are simply too many caveats to really embrace the idea.
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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