Re strange problems with graphics, Freezing

  Audio~~Chip 23:53 05 Oct 2009

no BSOD's so confused now what the problem could be firtly my Specification:

WinXP Pro SP3 fully patched
Asus P5QL Pro Latest BIOS v1004
Quad Core 9550 2.8GHz OEM Processor
Noctua NH-U12P CPU Cooler
4GB Kit of Crucial DDRII 1067MHz
CoolerMaster RealPower 700w Modular PSU 80+Cert
Samsung SH-223 DVD Wtr
PowerColour HD4850 PCS+ 512MB GDDR4 HDTV DVI-Out
Logitech Wireless 1500 Rechargeable D/top USB/PS2
Western Dig WD5000AAKS 500GB SATAII Caviar Blue

The problems, freezing at random, had some Black Screens if changing resoloution not the usual flicker but constant as if the Graphics card is unable to operate higher than 1024x768 stable

Then, I get sometimes fast boots and sometime sluggish boots. Maybe just me on this problem.

Now for the strange one; if I unplug the machine from say the wall socket, plug it back in (usual power applied to wall socket and usual Green Power light on Asus motherboard lights up) then power on the machine from the case and power points in the room are knocked off and the Fuse box in house needs to have the switch flicked on again to bring the power to the wall sockets. No lights go out and no other rooms effected as each room is on a seperate circuit.

The USB Ports work fine, from my experience USB ports fail when there is a dodgy PSU.

Any of the regular forum members have any ideas. Would it be a PSU problem shorting out maybe or another component causing this.

Appreciate this to be sorted fast as I have som many days left before I have to deal with Mfrs and not the supplier for any returns.

  OTT_Buzzard 11:08 06 Oct 2009

Try Marg7's idea of plugging into different part of your ring main.

Other than that, all the symptoms you've described are those of a faling PSU. USB ports will only fail if a specific part (5v rail) of the PSU fails.
Your graphics card will use a different part of the PSU to power it.

To elimate other possibilities:

If it won't invalidate your warranty on anything, then it's worth pulling your PC apart and cleaning any dust out. Household dust isn't generally very conductive, but on rare occasions it can lead to shortouts.

If you have a different graphc card you can try that wouldn't be a bad idea.

  Audio~~Chip 12:51 06 Oct 2009

I built the machine, have another machine in the same room but on a different socket and surge protected also changed them round with same problem. Have tested PSU with a Antec PSU tester and it was fine.

Have re-connected all the cables from the PSU again and problem seems to have stopped. Possibly might have been a loose connection from one of the Modular PSU Cables Molex end to the rear case fan not contacting correctly. Its a case of now seeing how things go.

Maybe something or nothing, which I hate when you never 100% know the cause.

Thanks OTT_Buzzard & Marg7 for your suggestions and I will see how things go.

  OTT_Buzzard 13:15 06 Oct 2009

Take out the motherboard assenbly from the case and test on a non-conductive surface (e.g. a wooden table). It will eliminate any possibility that components are shorting in the case.

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