That's not that great actually, considering it does quite all-right in 8x/8x, which the 975x, the RD600
D, bad joke, I know) and ASUS' P35 cand happily provide. That being said, out of those, only one will support Penryn, whilst the X38 is guaranteed to support it so...
Crossfire runs @ 8x / 8x for 975X
Crossfire runs @ 16x / 4X for P35
Battlefield 2
975X crossfire 117.2 FPS @1920x1200
P35 crossfire 111.5 FPS @1920x1200
Serious Sam 2
975X crossfire 137.1 FPS @1920x1200
P35 crossfire 124.5 FPS @1920x1200
F.E.A.R.
975X crossfire 97 FPS @1920x1440
P35 crossfire 88 FPS @1920x1440
http://www.anandtech.com/video/showdoc.aspx?i=2990&p=4
Supreme Commander
975X crossfire 38.1 FPS @1920x1200
P35 crossfire 28.2 FPS @1920x1200
Company of Heroes
975X crossfire 116.2 FPS @1920x1200
P35 crossfire 96.8 FPS @1920x1200
Prey
975X crossfire 108.1 FPS @1920x1200
P35 crossfire 83.3 FPS @1920x1200
http://www.anandtech.com/video/showdoc.aspx?i=2990&p=5
---------------------------------------------------
Overall, our game testing indicates that driver optimizations will be paramount to improving CrossFire performance on the P35 chipset when utilizing Vista. Due to the x16/x4 limitations, the expected performance capability of the R600, and a whole new generation of games coming out over the next few months that promises to pound your current system into submission at the highest settings, we cannot recommend the P35 at this time for a CrossFire capable system. That honor still belongs to the chipset that refuses to die, the 975X which is slated to be replaced this summer with the new X38 chipset. While not always the fastest solution for an R600 CrossFire platform it does offer a level of consistency and stability that is not always present on the P35. We fully expect the P35 to perform significantly better in several areas once AMD has the time to tune their drivers for it. For now we understand and accept this lack of optimization, but that does not mean we like it.
http://www.anandtech.com/video/showdoc.aspx?i=2990&p=6
---------------------------------------------------------------------
Will be interesting upcoming benchmark to see Crossfire for X38 @ 16x / 16X vs. Crossfire for 975X @ 8x / 8X