Originally posted by: macachia
so technically the ocz 520w is better than the ocz 600w for sli systems? (520w has 1 12v rail at 33a, while the 600w has 2 12v rails with 20a and 18a respectively)
http://www.ocztechnology.com/p...werstream_power_supply
I'd say it depends on usage (what & how many devices) & how the PSU is configured as not all dual rail PSUs are designed the same way. i.e. one dual rail PSU may power the CPU on one rail & everything else on the other, while others could have the CPU & motherboard on the same rail. Then there's finding/figuring out if the PSU can share it's amps or if it's amps are independant to their rails, among other possible factors.
Therefore I'll go back to the original question which was (to my knowledge), is a 520W single rail OCZ better than a 600W dual rail OCZ for SLI to which I said it depends. For safety reasons we don't want to max out the rails so we'll say you can only use 3A less than the limit on a rail, so 30A allowed usage for the 33A 520W OCZ & 17A/15A for the 20A/18A 600W OCZ.
So if CPU/MB = 17A & PCIe 6-pin+drives+fans = 15A of power consumption & you were to use a dual rail PSU that powered the CPU/MB on one rail & everything else on the other. That would give you a power consumption of 32A total (17+15). Sticking to the -3A safety margin, the 30A 520W OCZ would be 2A short while the 600W is capable. Although it may be difficult to get an exact power consumption based on that scenario, it is reason nevertheless for choosing the 600W dual rail over the single rail 520W.
To counter that we'll say PCIe 6-pin+drives+fans = 19A & CPU/MB = 9A - probably difficult (impossible?) to obtain as well. Power consumption total is 28A (19+9) total but in this case 19A on one rail exceeds one let alone both 17 & 15A rail limits by at least 2A on the 600W OCZ, therefore a single rail PSU is preferable.