1st. was a cheapo no name 550W (i think it was)
2nd. TT Toughpower 750W (bought used)
3rd. Antec truePower Quattro 1000W

it is not really a high power system, motherboard is Asus rampage gene II, gfx is MSI GTX275 Lightning and OZC revodrive

So I thought 1st powersupplay - well niname, they die coz they sucks
2nd. ok it was used, perhaps it was defective (worked for 8 month)
3rd. I thought ok well, either the motherboard og the gfx is killing the psu..

So whitch do you think it is?

I can plug in a new PSU and everything works fine, but for how long? :)

i recommend an office space moment with your computer in a friends feild

that;s weird. do you use an avr or ups? and the gtx 275 lighting..do you have it overclocked & overvolted?

Could be your power supply...do you have a surge suppressor and/or a battery backup that your computer is plugged into?

Are you blocking the fans?? Or even the whole case?

a computer shouldn't be able to kill a PSU; a good quality PSU ought to be able to have a short across the rails and handle it (ie fail gracefully)...

though yea as somebody pointed out it could be the power to your PSU.. ie your residential power or whatever; a good quality surge protector can make a world of difference if you're on sketchy power (especially in areas with lightening + above ground wiring)

I have a cheap Asus mb and an Asus GTX275 on my 500W Zalman psu. Has worked great for 2½ year even though I shortcircuited a 12v outtake while trying to fit a mini amp at reversed polarity into it (surviving even though the cable jacket melted).

GFX is stock and CPU is also stock no overclocking

Right now the computer is connected to mains directly, when it killed the 750W is was connected via my UPS.

the 750W power supply could be connected to the mains but when you tried to start it it turned the fan and power led on the motherboard lid up for 1 sec or so then it shut down (so some internal protection in the PSU)
The 1000W just trip the main fuse as soon as it is connected to mains
can't remember what the niname did

The case is dust free and BIG, så plenty af air around/inside it

1000w PSU for a system that pulls probably 350w on a good day lol. nice.

did the PSU work at all or did it not work right after installing it?

PSU worked fine for a year

it did pull 420W when the gfx and cpu was busy running seti@home :)
but yes, a good 550W is plenty for that system, witch is also strange why the PSU's keep dying

(perhaps they are made by PDM) :p

Mine reaches 420W with furmark + cpu benchmark running at the same time. 350W or so max during most games.

dust etc, or bugs? I know someone else who kept killing PSU's because of both of the above. I got given the case and mobo etc, put a new psu in kept it clean and all worked fine

Nu dust to talk about...

was the computer shutting down due to brownouts?
run diagnostics on the mb?
if i was going to guess between mb and gfx, i'd go with mb since that should be where power management is located.

yes it shut down in the middle of a CSS game, and I was winning!
(as usually) :)