Powmax has a pretty bad reputation, most of it apparently deserved. They seem to be involved in a disproportionately high number of bad PSU issues here on AT, although that is not truly conclusive (it may just be that, because they sell for cheap, they sell more PSUs, and so we see more issues involving them because more people are using them).
As for this particular PSU:
Max Load: +3.3@32A, +5@40A, +12@24A, -5@0.5A, -12@0.8A, +5vsb@2A
Those are pretty respectable specs (assuming it can actually keep them up in real operation).
However, I'm not sure if those are accurate specs for this PSU. From
Powmax's Website:
SPECIFICATIONS
Model: PSDE580
Dimensions 6"Wx3.6H"x6.6"D
AC Input 115/230, 10A/6A, 60Hz/50Hz
Max Load +3.3@28A, +5@38A, +12@17A, -5@0.5A, -12@0.8A, +5vsb@2A
MTBF 100K hrs at 25°C ambient conditions
Efficiency 70% Min. at full load
Noise Level Maximum of 37db at 100% system loading
Certified by UL, CB, CE, TUV, & FCC
(these add up to ~480W, and indeed the "Demon 480W" has the same specs, so maybe this is just a typo on their page. But it's still not a good sign if they can't keep their own products straight.)
I'm highly skeptical that this PSU could consistently output nearly as much power as it claims. It's worth noting that the Antec TruePower 550W has the *same* specs as Newegg gives for the Powmax 580W PSU -- and I somehow doubt that the Powmax one is *better* than the Antec (which costs ~3x as much, and in its
specs page it's even limited to *530*W on those lines). However, you would need to do some serious PSU benchmarking to truly determine how good it is (the kind of benchmarking that SPCR and THG do, where they stress the PSUs to their limits).