I bought a logisys case with a supposed 480W PSU. The stickers says +3.3V & +5V = 200W and 3+.3V & +5V& + 12V = 330W and says total average output is 330W. Why all of the sudden under it says Total max Output = 480W. Btw, it could not power my P55A -UD3 rev 2.0, Intel i5 760 quad 2.8 , and HD RADEON 5770. The PSU has a 4 pin PCIe power connector, although the GPU has a 6 pin, it says it case run. Off of a 4 pin. Why?
Yeah, never ever use a power supply that comes with a case. That 4 pin is for the CPU on the motherboard. I would get another power supply.
I did end up getting an antecedent 540W gaming PSU, But I already have a 4. Pin plugged into the motherboard. The 4 pin fit in PCIe power port on my 5770, but would I be able to use this PSU to power another computer with lower energy consuming parts, or no dedicated video? Or even my old p4?
You cannot use one in the wrong place. They are wired differently. Using one in the wrong place will result in shorting 12 volts directly to ground. If you are lucky, the PSU will detect the short and nondestructively shut itself down. If you are unlucky, you can fry something expensive.
You have a 330 watt PSU (total average power). Any other rating ("peak" or "total" max power) is meaningless. Even so, a 330 watt PSU (if it can actually produce 330 watts) should be able to power your system.
I estimate that total PSU load on your system is around 250 watts.
Yeah, never ever use a power supply that comes with a case.
Not always true. The power supplies that some Antec cases come with are quite nice. More accurately, never buy a case/PSU combination that costs less than $70.