AMD's CrossFireX: Tri & Quad GPU Preview
by Anand Lal Shimpi on February 21, 2008 3:00 AM EST- Posted in
- GPUs
The Drivers
Make no mistake, we are dealing with the earliest drivers AMD was willing to let out of its control - in other words we should expect bugs.
Much like our Radeon HD 3870 X2 experience, CrossFireX just worked. Switching between 2, 3 and 4 GPUs did require a driver reinstall for things to work perfectly but once we ticked that little CrossFire checkbox everything worked as it should.
CrossFireX: Don't Feed After Midnight
The rules for CrossFireX are simple: you can make any combination of up to 4 RV670 based GPUs, using either Radeon HD 3850s, 3870s or 3870 X2s. Note that the upper limit is two Radeon HD 3870 X2 cards (4 GPUs).
While the clock speeds aren't normalized to the slowest card in the arrangement, the faster cards will have to wait on slower cards so ideally you'd want to pair similarly clocked GPUs.
Two Radeon HD 3870 X2s in action
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Pirks - Thursday, February 21, 2008 - link
Do they speak English in "what"? (C) Pulp FictionNever mind, just kidding :)
Griswold - Thursday, February 21, 2008 - link
What!?skiboysteve - Thursday, February 21, 2008 - link
"What were 70 - 100% gains from 1-to-2 GPUs are more than cut in half, becoming 30 - 45% gains when you add a third GPU"this should be expected...
If each card provides 50fps in an ideal case...
1card at 50 fps
2card at 100fps = 100% improvement over 1 card
3card at 150fps = 50% improvement over 2 cards
4card at 200fps = 33% improvement over 3 cards
The most it can possibly provide is 100%, 50%, 33% improvements at 2,3,4 cards.
Noting that, COD4 scales incredibly well.
dustwalker13 - Thursday, February 21, 2008 - link
exactly what i was thinking ... cod almost scales ideally right up to 4 gpu's ... that 'somewhat reasonable gains' statement would fit HL2, which is scaling with every gpu added but the benefit diminishes. cod is scaling almost optimal:gpus - max scaling - actual scaling
2gpu - 100% - 98%
3gpu - 50% - 44%
4gpu - 33% - 29%
RamarC - Thursday, February 21, 2008 - link
i'd like to see how it handles mismatched cards in 3/4 way configs. another site did a crossfire review with a hd 3870 paired with a hd 3850 and their combined performance approached a hd 3870x2.Bladen - Thursday, February 21, 2008 - link
I'll say.I am very surprised to see "unfinished" drivers and tech preforming almost optimally, albeit in only 1 test case.
I think AMD should heavily encourage Infinity Ward to licence out COD4's engine.
Griswold - Thursday, February 21, 2008 - link
"I think AMD should heavily encourage Infinity Ward to licence out COD4's engine."Oh please, no!
Samus - Thursday, February 21, 2008 - link
Yea, frak that. COD4's engine doesn't have the feeling or capability of the source engine, which scales great (except for the 4th GPU I suppose.)With more tweaking, the Source engine is most ideal. Obviously they shouldn't target Crytek's engine, though.