Computer Instant Power Off

[d_hall81]

First of all thank you in advance to anyone who can help me. I've been having a few problems with my computer since a (seemingly bad) upgrade.

I've upgraded my machine with the AMD Radeon 7970 (MSI overclocked edition), however now whenever I start an intensive game (like The Sims 3) my computer seems to power off instantly during the games loading screen. I've checked by running the monitoring utility on my second monitor and there seems to be a spike in GPU usage during this period. After it's powered off instantly (I don't mean crashed, or frozen etc just literally like I'd pulled the socket out the wall) the computer will not turn back on again until I flick the switch on PSU off and back on again, then I can use the power button on the computer to turn it back on. My question then: is this a problem with my PSU or something altogether different?

As a side note that may be important, during these loading screens my computer also makes a strange high pitched whistling noise (like an old kettle boiling over)

 

[C12Friedman]

It seems to all be PSU related - the high pitch whistle is usually caused by a coil within the PSU (caused by resonance - not important), it does not in itself have any real significance (other than the annoyance factor). But it seems that your PSU cannot handle the load of the graphics card - if it is an older PSU or older design, it was never meant to. If this was a pre-built system, they are usually built with a minimal power supply which is adequate to handle the pre-built's current draw and not much more (7970 is a lot more).
I'm going to suggest you replace your PSU with a quality 500W one of these brands (PSU's are not created equal)... Antec, BeQuiet!, Corsair, FSP, PC Power & Cooling, SeaSonic, Super Flower, or XFX. But check the reviews (this list has links to legitimate reviews http://www.realhardtechx.com/index_archivos/Page541.htm - newegg doesn't count) as even within those brands, there are 'lemons'

 

[mlcaouette]

+1 to the PSU, seems like your PSU is about to blow. Replace it before it does, using the suggested brands above.

 

[d_hall81]

It seems to all be PSU related - the high pitch whistle is usually caused by a coil within the PSU (caused by resonance - not important), it does not in itself have any real significance (other than the annoyance factor). But it seems that your PSU cannot handle the load of the graphics card - if it is an older PSU or older design, it was never meant to. If this was a pre-built system, they are usually built with a minimal power supply which is adequate to handle the pre-built's current draw and not much more (7970 is a lot more).
I'm going to suggest you replace your PSU with a quality 500W one of these brands (PSU's are not created equal)... Antec, BeQuiet!, Corsair, FSP, PC Power & Cooling, SeaSonic, Super Flower, or XFX. But check the reviews (this list has links to legitimate reviews http://www.realhardtechx.com/index_archivos/Page541.htm - newegg doesn't count) as even within those brands, there are 'lemons'

Thanks so much for the reply. I'll check out that link now, my current PSU is an OCZ StealthXStream 700 (though obviously quite broken) does this mean I'll need a new 700W PSU or will a lower wattage be adequate? Or more to the point is there a simple way of determining the required wattage?

 

[mlcaouette]

Just use a power supply calculator to determine your needs:
http://www.extreme.outervision.com/psucalculatorlite.jsp