Terrible voltages on 5v -5 and 12v rails regardless of PSU

Backstory:

Arround 6 months ago I had a x800 xt graphics card fail on me after just three short months of use(from new), sience then I replaced the card with a x850 xt. Sience having the x850 however I began to notice frequent crashes to a black screen(Only while playing more upto date games however), causing my moniter to go into standby mode as though the graphics card stoped sending a signal, rebooting the machine fixes the issue, although it is likly to reoccur again after some random time interval.

The problem:

Attempting to resolve the issue I began monitering my PSU voltages (Using SiSoftware Sandra 2005), and noticed when *idle* my voltages did soem strange things. While my CPU, +3.3v and +12v were all reletivly fine(1.40 stable, 3.6 stable and 11.0 - 11.9 respectivly) the remaining voltages were far from ok. The folwowing are taken while playing Day of defeat source for arround 20 mins


After my mainboards on board lan chip burned out(presumable because of this faulty PSU) I replaced it with a Tagan 480 U22 PSU, as based on reviews there were none better value, perfectly stable PSU's out there. You can imagine my horror however when after a few mins idle SiSoftware Sandra gave the the folowing readings:


The question:
Just how worried should I be by these readings? Is it likly that my graphics card is in fact to blame for them rather than my PSU? Or perhaps my mainboard? (Unlikly as the x800 was 100% stable before it failed randomly one day) Any and all help offered is strongly appreciated, as this problem is really starting to get to me, Ive now spent over £900 string to get this system working(inclucing an initial £600 for the original x800 setup, oh how I wish that card hadn't failed...) so any ideas are more than welcomed!

The specs:

Tagan 480 U22 PSU (brand new today)
Saphire x850 xt 256mb GPU (~3-4 months old)
AMD 3500+ winchester core CPU (~6 months old)
Gigabyte GA-K8NXP-9 MAINBOARD(~6 months old)
maxtor 80 GB IDE HD(~2years old)
maxtor diamond max 10 300 GB SATA HD(~2 months old)
CD ROM (unknown age)
Nec DVD RW+/- (~6 months old)
floppy drive(unknown age)
2x case fan(in addition to CPU AMD 64 arctic silencer and GPU arctic silencer)

Did you check the PSU rails w/ a volt meter?

Can't say I have, I figured with voltages that far out, and problems so obvious there must be a problem present in the voltages even if the recordings are inaccurate.

When the screen goes blank does the rest of the system keep running or is it a total lock up?

The voltages you report are well below and above the regulation if that really is happening then the power supply should stop giving the power good signal which would causes your system to lock up.

If we take thos voltages as gospel then It can only be one of 2 things either a faulty PSU or something is causing the power supply to go out of spec, why or how this would happen I have no idea.

You say one graphics card has already failed and the mobo onboard LAN chip has burnt out, this to me makes me point a great big grubby fat finger at the mobo.

For my money I would get a multimeter and check the PSU voltages, at least you could rule one thing out.

Thanks max, firstly to answer your question it appears to be a total lockup coupled with looping sound, only a hard reboot(cable pull or button) will get out of it. The failed x800 problem was similar, only without warning it simply stoped giving any output to my moniter(which remained on standby), it was fine one evening and when I started it the next day the moniter recieved no signal, no warning beeps from the computer however which seamed to start normally without any screen on the moniter.

The most frequently crashing games are Dawn of war(though rarer than most), full spectrum warrior crashes repeatedly at certain areas of the game(to the point I cannot progress past those areas)

Hl2 and its mods crash inside 30mins usually, but strangly the mod Plan Of Attack never crashes, similarly DoD source crashes rarely and CS S always crashes(last time I played it crashed and my on board LAN chip has burned out). All of these crashes produce the same blank screen effect, coupled with a rarer game only freese up(leaving the frozen image of the game + looping sound)

The strangest thing is my system appears 100% stable outside of more upto date games, I can run it for days straight without any crashes. I have played a number of games without it ever crashing too (HL1 and mods, a freeware 3D FPS "war rock", any 2D game, in fact it seams any non shader intensive games....)

I guess Ill have to try and get hold of a volt meter. I belive the voltages are supposed to be within arround 10% of thier original, although within 5% is best?

After that I suppose I could try replacing the mobo, only problem being this model doesnt seam to be available anymore so I may have to switch to a different vender, any recomendations on a top performance AMD 949 PCI-E mainboard? I would concider a crossfire one. I strongly belive the vid card is the culprit tbh, but that would cost 200+ to replaced compared to 60-100 for a mobo.

Does anyone know for certain how important the -ve voltages are, and has anyone heared of these going positive before? It seams impossible in my head? Ive heared theyre completly useless?

Also is it true the 5v rail is just for levling out the . and CPU voltages?

Thanks again all... now to find a voltmeter...

[EDIT - oh one more thing, the LAN chip burnout was a funny one, caused windows to reboot infinatly untill the HD was formatted. Then when windows boots any attempt to install the on board LAN drivers would cause the infinate windows reboot loop again. Disabling the LAN chip in the BIOS fixed the problem however]

the - voltages are not important anymore.

5% is the max deviation. Some PSU manufacturer's will be tighter than 5% but 5% is the deviation allowed by ATX specification.

I would suggest measuring with a DMM before going any further.

+5v is used for more than what you mention. USB, molex's, PCI-E, SATA they use +5v line. Not very much overall but they still do.