It can depend a lot on which games you play. Some games make poor use of multi-GPU resources, many games are not AMD-optimized (because they're NVidia-optimized), and a few games (like
BF4) combine worst-case extremes in a way which gives truly dismal performance gains from CrossFire. Game/Catalyst patches and updates can sometimes help a lot.
Just covering the basics -
- Your bridgeless CrossFire link may be saturating the PCIe bus, remove or disable any PCIe cards you don't need. (Oddly, in this instance you might actually see more fps with a regular SATA SSD RAID than with your RAIDR card.)
- Your BIOS might have options for PCIe lane allocation or signal prioritization which can help.
- You could also try bumping your PCIe bus voltage in the BIOS. This doesn't ever seem to really do anything useful (and is usually best left untouched), but this seems like a situation where it could make a real difference.
- Your two 290X cards will suck a lot of power at full load, hopefully your PSU is beefy enough and you've used the optional GPU-boosting motherboard power connector so the GPUs aren't being throttled. (I think your 1300W PSU should be good enough ... but those high-end AMD cards are real powersucking heat pigs.)
- Your system might be throttling the GPUs because they're too hot, if so then you need a GPU cooling upgrade.
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