Do you need a high quality PSU? No. Not really. There are millions of PSUs in the world which are powering computer all over and do so just fine. The problem is that the cheap ones have poor quality control, are often out of spec, and sometimes even flat out lie. When they are out of spec or lie, you could end up damaging your entire system. There is a pretty bad myth that you need a really high power PSU. That is completely false. Most of the time, you use under 100 W when idling, and just over 200 when at full load, less if you don't have a graphics card. That's why OEMs can get away with cheap as hell power supplies. It's easy to make a 200 W PSU.
Should you want to learn about power supplies, you can read up:
Why 99% of Power Supply Reviews Are WrongAnatomy of Switching Power SuppliesHardwaresecrets' testing methodologyThere's a few things which make a good power supply. The first is the minimum specifications (found in the primary and secondary analysis in HWS). Many cheaper power supplies end up leaving out some of the more expensive parts (IE the MOV in the OCZ stealthxstream 2). The second is the quality of the parts. To put it bluntly, and generally, Japanese > Taiwanese > Thai > mainland Chinese components. Japanese capacitors are typically designed to tighter specifications and thus are of better quality. That comes at a significant price, however. The weakest component is the limiting factor in the performance (and lifespan) of the power supply. If one thing dies, it's dead. Finally, the actual performance of the PSU matters a lot, probably the most.
Ripple is measured with an oscilloscope, and it's supposed to be a flat line, but that's impossible. If you have too high of a ripple (probably in the 160 mV range) you can damage your components. The ATX limit is 120 mV for the 12 V rail, and 50 mV for the 5 and 3.3 V rails.
Voltage regulation is the actual voltage being supplied to the computer. ATX limits within 5%, most good PSUs do 2-3%. That means the 12 V rail can supply from 11.4 V to 12.6 V. Obviously overvolting can cause damage to components, and undervolting can cause crashes.
You also need to pay attention to the current on the different rails. The one you listed has 4 12 V rails. That means there are four "mini" power supplies delivering 20 A to different wires. Generally, one rail is better, but separating the rails is supposedly safer, because if one rail fails, you don't kill whatever components are attached to the other rails. Some graphics cards may require a lot of power one one rail, other times it's hard to see which rail belongs to which wire, so you don't plug everything into the same rail by accident.
Efficiency is somewhat important, but really only calculated. It's a good idea to be more efficient, but virtually every PSU now is at or around 80%, rather than 70%. The EU has much stricter (and much more efficient due to 230V) energy system, so anything you get will be quite efficient.
Finally, the power correcting factor. If it has a PFC, then the power factor is probably .99 or around there. If it doesn't, then it's around .6 to .7. having a high power factor reduces loads on the power grid significantly, though you're only charged for the power you actually use. It's a bit hard to explain because I don't understand it very well. Suffice to say, PFC is good, but it doesn't directly save YOU money, it saves the electric company money by raising efficiency. The one you linked has a passive PFC. That means you'll need to flip a switch to say whether or not it's 115 V or 230 V coming in (unless it's EU only, in which case you can't ever use it in the US). Passive PFCs are supposed to be more efficient, but I think it's negligible on computers. An active PFC means that it automatically adapts to any input voltage. There is no switch, and you just plug it in. If the PSU doesn't have a PFC, which is/will be illegal in the EU, then it will also have that switch.
A note I just found on the MOV:
Its main component is called MOV (Metal Oxide Varistor) or varistor, labeled RV1 on our schematics, which is responsible for cutting voltage spikes (transients) found on the power line. This is the exact same component found on surge suppressors. The problem, though, is that cheap power supplies dont carry this component in order to save costs. On power supplies with a MOV, surge suppressors are useless, since they have already a surge suppressor inside them.
If you use a surge protector, you don't actually need an MOV. So don't plug it directly into the wall.
tl;dr;
Your (new) computer will draw somewhere under 500W of power. Having a good 600W PSU means good quality, high efficiency, and good stability. Having a cheap 750W PSU means bad quality, mediocre efficiency, and probably good stability. You won't notice the difference, but considering you won't and should never be drawing more than 500W of power (unless you have 2 cards or a 3 million transistor GPU), there's literally no reason to have that huge power supply. You don't gain anything from it. It's a difficult concept to realize that more =/= better when it comes to PSUs.
All that being said, I successfully used a 500W free after rebate, no PFC power supply for a long time with a more power hungry setup than you have now, and it worked fine. Chances are the cheap power supply will work for you. What you're paying for is sort of like insurance. the cheap PSU could kill your stuff much easier than the more expensive one. That's why people say not to skimp on the PSU and that's its the most important part.
Edit: I found your exact PSU, and it's got a terrible review, and it's in german:
http://www.planet3dnow.de/vbulletin/showthread.php?t=373122&garpg=8
Post has been edited 1 time(s), last time on Dec 7 2010, 4:44 am by rockz.
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