PSU Problems?

[lammer]

Hi There
Before I start I know its old hardware but I'm not a gamer I use the machine for Music production hence the duel head card and the two sound cards the Sb is only to give midi in/out.
I've been maxing out my mobo Asus P5PE-Vm its had 2Gb of Ram and a Pentium D945, Echo Gina, Sb Live, Matrox G450 duel head graphics card in for years. I just got a core duo E6700 2.66GHz about the fasted thing it will take at resonable cost over improvement. That was all fine. Then I was given a Thermaltake case and decided to build into that until I go for the full Mobo Proc Ram upgrade maybe next year. I thought I may as well change my PSU too as mine was only 300W. So I got a Qtec 550w off of ebay still in its box and sealed with the celephane. Done the build switched on everything came on for about half a second and then nothing except the green indicator on the mobo. Tried my old supply bingo all working. Tried the PSU in another machine with asus P4-800 deluxe P4 3Ghz overclocked to 3.6 and again nothing. So heres the rub I shorted the PsU Green to Ground thats power on to gnd and presto the psu starts measured the voltages and well, their all there and about right. So took it out and tried it in yet another pc Old Amd XP2000 and a V266 mb hit the switch and away it goes. Also plugged into a couple of P4 mbo i've got laying round and workrd with those too. I have another Asus P4-800 not a deluxe but without trying quess that most likely wont work.The 5V is there on the Violet wire and the power switch makes the power start if only breifly. What appears is not happening is the return from the mobo and the power good arn't there or too slow to appear " A guess!" So the question is WHATS UP? is it an asus thing a Qtec thing or just something that happens when the two are put together? Or am I missing something simple?

 

[rolli59]

Based on the lack of information available at manufacturers website and this unprofessional review http://modtown.co.uk/mt/review2.php?id=qtec550dfg I would blame it on the low quality of the PSU!

 

[lammer]

Yep poor review, pink is tacky, blue is better red works best. I just want the thing to work. The tested labels must be stuck on for asthetics only as no real testing could have gone on. Question is it faulty, as in not working as it should?or is it S**t and working exactly as it should? I feel ripped off at the £5 I paid on ebay if i paid the £49.99 it should have cost i'm affraid I would have to throw it back through the shop window with a note on it. Can any body direct me to a circuit of an Atx supply so that I can see whats actually is supposed to happen. I know the green is grounded at switch on and the power good locks in when the power is stable but what keeps the supply running till then? Do all motherboard do it the same way?
Also with the different versions of ATX form factor is it just a case of redisributing the power through different connectors or are there other changes. I've modded many a psu to run P4 Mobos by adding the 4 way socket. and rewired standard ones to fit Dells. Its just that I thought the violet 5v gets fed back to the psu via the M/B when the Green power on is grounded does the green remain grounded under control of the M'B or is it released and held on by the power good line?