Hey all, I just got done with building my second a64 rig, its another dfi-nf4 sli-dr mobo, same as the one in my sig, with a 3500+, and 6800GT pci-x. My ? is, I have a month old Antec TrueControl 550W PSU, and I was reading around on some sites, that I might not need to get an adapter for 20-24 pin, that if I have a quality PSU, I can just connect it as the 20 and leave the top 4 open. I just didnt know. When I built the one in my sig, I just went for the OCZ powerstream 600 and was done with it. I just dont want to ruin this PSU.

you can do that, but you need ATX 2.0 for SLI. I would recommend a 2.0 PSU because of the nvidia card and SLI capability.

PSU FAQ

I think it goes you can leave the 4 pins open and it will be ok if you don't use sli but if you use sli it is recomended you use an adapter or get a 24pin ps.