Best X58 1366 CPU for Gateway FX6800-01e motherboard?

[lignimvite]

I have the i7 920 in it right now and I'm wondering if upgrading to an i7 975 or Xeon X5680 would be better because both are around $50 on eBay. I don't think the board can overclock and I'm using the stock air cooler so I probably couldn't much even if I could. I looked around online and I can't find the manual or compatible CPU list other than on UserBenchmark which lists up to the 975. Would it be worth it? I have a GTX 460 SE which I plan to upgrade to a 1060 6GB since I have an ultrawide and 1080p monitor.

 

[spentshells]

Just go with the 975, the motherboard being a pre-built with custom bios options may not support the xeon