BSOD error seem inconsistent/different with PC problem

i have another PC.
i bought a 22-inch Chimei LCD, for that PC, back in February. i have seldom used that PC since then.
i have encountered a problem with it, which has never happened before ---- the PC automatically shuts down. it happened again today (it's the 2nd or 3rd time it happened).
pressing the power button does not/cannot turn the PC on (PC does not boot). but i noticed the keyboard & mouse are still lit on (remember the PC is off). i can turn the monitor on too, but of course, there is no image/monitor is black.

the last time it happened... what i did was let the PC rest for a few minutes, reconnect the power cords to the AVR (auto. voltage regulator), then it turns on & works ok, like nothing happened.

if it helps, that PC has been having a ringing sound during boot time, since mid2009-Jan2010.

i do not have an idea what the cause is.
but my guess is that the problem has something to do with the new monitor.
the old monitor was a 15" samsung LCD.
..another guess is the power supply. since i upgraded to a bigger monitor, this may be related to it. (a few minutes ago, right after the PC auto shut down, i touched the Power supply casing it was relatively hot)
my power supply is 300W, it came with the PC when i bought/assembled it around 6yrs ago..


Hopefully someone can help
Thanks all!


*****************

Greetings all!
i've written & posted the above post last July 6, 2010 in another forum.
within 1week of that posting, i replaced the 300W PSU with a new 500W PSU.
below was my July11 post

i bought a new one a few hours earlier.
i just tried it.
during the first attempt i still heard a ringing sound, but it was considerably shorter in duration & quieter in volume. (video card may be another culprit)
during the second attempt, it went smoothly.
Thank God.
will monitor it for about a week.

July12 - 16 2010
i still hear ringing sound during almost every boot-up.
PC automatically shuts down several times; a few times, it shuts down after a few hours of usage, much fewer times it shuts down in less than 1hour of being open. i was doing spyware check/antivirus check, leaving the PC on (with monitor turned off to save power), & when i came back the PC is turned off (but keyboard & mouse are still lit on).
trying to fix the problem myself, i used PC2's video card (Nivdia geforce MX 440). PC1's video card is Inno3D Geforce FX 5500. using PC2's video card, i never heard a ringing sound. seeingthis, i suspected the FX 5500 is the culprit. in the other forum, a poster mentioned changing the Video card solved the "auto shutdown" problem. so i thought this was the cause.

July 17, 2010
i was able to successfully install a wired router connecting this PC (the PC im using right now; i installed the router in this PC; from now on we'll call this PC2) & the above mentioned July6 PC (which we'll now call PC1). that day i was able to use PC1 surfing the internet, using PC1's FX 5500 vid.card.

July18
when i tried to use PC1, (FX 5500 inside), during boot up. i got a BSOD.
the stop error message was
0X000000ED UNMOUNTABLE_BOOT_Volume
specific info found on microsoft support page & kadaitcha website
(it's my first post, so im not allowed to post links)

im surprised getting this error message because, i didnt install any new hardware or software. i had PC1's original video card installed, which is the Inno3D Geforce FX 5500.
i never touched/removed the RAM, or any connectors/device/component etc..... i only installed/removed the FX 5500 vid.card (to test if it is the one causing ringing sound/auto shutdown)

i can remember doing a minor change on the BIOS settings.
on "Primary Graphics Adapter", i changed it from "PCI" to "AGP"
(i went inside the BIOS settings primarily to check if video card "Fastwrite" settings is Disabled, well it was Disabled; 'Fastwrite' was mentioned to be 1 of the FX5500 problems in a few forums)

the stop error message seem 'inconsistent' with my assumed video card-led auto shutdowns.... unless the BSOD is a harbinger of much worse PC problem.

AMD sempron
1.5GB RAM
i will give more details about my PC specs tomorrow. (i'll try to boot PC1 again to get details)
{i checked several times; there are no blown/burnt capacitors/MOSFETs}


any insights/replies will be appreciated. Thanks & God Bless!!!!!!
 
For PC2 (which initially seemed to have shutdown issues) please look into Event Viewer Logs, and see whether you can find something useful. I am unsure what that 'ringing sound' means, I hope someone else can shed some light on it.

For PC1, check that the DATA cable is correctly connected, this can also be caused by wrong cable, i.e. 40 pin cable provided that its a UDMA drive requiring 80 pin cable.

Or according to MS this can also be caused by wrong configuration in BIOS, i.e. forcing the hdd to boot with faster UDMA settings.

Last but worst case is, the file system is simply damaged and can't be mounted, to check that out you can download test disk and check your disk with it (you will need to attach it with a working PC). Regards
 
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