First I think you have to make a choice between DDR2 and DDR3.
If you go DDR2 then XFX and EVGA 780i is the choice coz ASUS still have the "CPU INIT" problem with Striker II Formula.
And major additions to the nForce 780i SLI chipset include support for NVIDIAâ€™s ESA standard and PCI Express 2.0 support through the use of the new nForce 200 chip. Other than those two additions, the nForce 780i SLI is almost identical to the nForce 680i SLI, which is not surprising considering the 780i SLI SPP and the 780i SLI MCP are essentially the same chips used on current nForce 680i SLI motherboards and gets hot when you OC, third part cooling on SPP (NB) and MCP (SB) is recommended.
If you go DDR3 then ASUS Striker II Extreme should be the choice, XFX and EVGA 790i isÂ´t bad either but it seems that Striker have the upper hand if you read reviews.
You have the support for NVIDIAâ€™s ESA standard and PCI Express 2.0 but not through the nForce 200 chip itÂ´s through the 790i Ultra chipset. ItÂ´s not even close to the 780i (680i) when comes to heat, 790i is much cooler and seems to be a very good quad OC.
I think the only issue with the 790i chipset right now are the corruption of data when OC, it seems that it comes as early as FSB 350, it can be related to which DDR is used, it seems that Nvidia chipset can be a bit picky about which RAM you run.
DDR2 XFX or EVGA 780i
DDR3 ASUS Striker II Extreme
ThatÂ´s me opinion.