Please remember that any mention of competitors, hinting at competitors or offering to provide details of competitors will result in an account suspension. The full rules can be found under the 'Terms and Rules' link in the bottom right corner of your screen. Just don't mention competitors in any way, shape or form and you'll be OK.
Not even safe to do GTX580 2-way SLI. Reason:
Just be careful with the HX1000 PSU, because it is essentially made of two 500W PSUs, and there is no load balance between the two +12V rails. Each +12V rail can only power up to 500W 40A, but the requirement for a single GTX580 in a complete machine is 600W 42A, which exceeds the requirement of your GTX580 which shares the same +12V rail as your CPU.
It might work fine. Many people have been running GTX580 SLI on HX1000 and never met any problem. However some unlucky people, including me, have encountered problems, mostly instability in such setup. It really depends on the quality of the specific sample of your HX1000 - if the +12V rail which is shared by your CPU and a GTX580 can overload some bit fine then it's fine.
If you decide to move to a new PSU, then the Corsair AX850 works great for GTX580 2-way SLI, because that PSU is a single rail, and you don't need to worry about load balancing between rails.
For TRI-SLI, the AX1200 or the HCP-1200 is the best choice. By overclocking with volt bumps to 1.15V on each card I saw my AX1200 drawing 1280W from the wall.
Thanks guys, new PSU it is then.![]()