Vista - My computer randomly powers down

Hey guys. I know this is my first post, but I'm having major problems with my Vista PC. It consistently has random power downs. The major problem is that I can't pin-point a source for them! I recently purchased an Acer M5260 from Best Buy. It's got:

6GB of DDR2 Ram
2.4Ghz Quad-Core Intel processor
HD3540 ATI graphics card
Vista Home Premuim 64-bit
Some no name motherboard that fits inside a small case.

I got it fairly cheap, and decided to upgrade some components. I bought a 650w power supply, an HD4870 ATI card, and a new, medium sized case (I forget the name. It has 4 fans and a gigantic one on the top. Obviously the motherboard is smaller than the case. Anyways, I installed the new components. Everything runs correctly except that my PC will now randomly shut itself down. I've tried checking the heat, but everything seems fine. I've run overclock tests and so on, but the computer passes them. Nothing particular seems to be the root cause. I can leave the PC idling and it will shut down. I can play a game for 2 hours and it will randomly shut down. I can play a game for 5 minutes and it'll shut down. I can immediately turn the pc back on, load the same game, and play for an hour. I can just be browsing the web and it will shut down. It can't be a heat issue so far as I can tell.

So, what could be causing it? I re-installed vista with my brothers 32-bit version of Home premium. It seems to be running better, but it still will occasionally shut down for no particular reason. I turned off Aero and it still does it.

Does anyone have ANY suggestions on how to diagnose the issue? Windows error check just says I've been having "Disruptive shutdowns" without giving a cause. I can post pictures of my pc if people need them.

Hi Dark Mirage, welcome to the board.
I would try open case test with a house fan blowing directly into it. Make sure good contact between the heatsink fan assembly and the CPU. If it is not heat problem, before you mess with the mobo, try another psu. Good luck and post back.

Thanks. I'll try the home fan thing tomorrow. I've gone through that problem before though and used a home fan... This doesn't seem to be the same. I'll give it a shot anyways though!

Argh, I really hope it isn't the power supply. I just bought this one a couple weeks ago too, so it's too late to return it. That'll be another $100 if it's not working correctly.

It sounds like it is...... If it is under warranty take it back. I believe all PSU have 12 months warranty

I believe you have to read this...
Continuously Reboot

It definitely sounds like a hardware error, not software. I am not sure what you mean by:

>Windows error check just says I've been having "Disruptive shutdowns" without giving a cause.

By "Windows error check" do you mean Event Viewer?

Vista has a good built-in tool for monitoring performance issues, and you can often troubleshoot problems by the method explained in this web page:
Fixing Windows Vista, Part 3: Top Troubleshooting Tools | Ed Bott’s Microsoft Report | ZDNet.com
Fixing Windows Vista, Part 3: Top Troubleshooting Tools
Let Windows identify performance issues

What are your CPU temps?

I would say its either overheating or your PSU is bad.

Download a program like CoreTemp and make sure the processor isnt overheating before you waste your time with the PSU.

Hi Dark Mirage.....when you say ''shut down'' do you mean it logs off & shuts down or just reboots..??

if there is no BSOD i would be inclined to think its one of two things...

CPU HSF, as stated above if this is not seated correctly this will cause an instant un prompted shut down, im guessing its a skt 775 CPU which means you probably have the crappy pushpins on the HSF....
these are a nightmare & what you think is locked often is not.

or the PSU, i know you said you bought a 650w PSU but what make & model..??
how many Amps on the 12v rail..?? how many other peripherals do you have..??
(please fill out sys specs )

the 4870 is quite power hungry, its requires you to have a 32A 12v rail minimum & draws around 330-340w under load

so unless its a capable PSU i would start looking there, the fact it restarts when the card is idle could show that the PSU is not only underpowered but is actually faulty....it happens quite a lot, i hear about bad power units all the time even with high end units, some just have unstable rails.

this is what i would do......

test the rig with a different PSU if this is not possible get a multimeter on the existing one to check the voltages. (google will help you do this)

if the PSU is not the problem check the HSF (especially the pins themselves)

i had a GFX card die on me once & that used to reboot continuously with no BSOD until i unplugged it, so you may want to try your old card with the new PSU this will confirm a lac of power or maybe a faulty 4870 (this is very common place too)

though this is all moot if it actually logs off & shuts down b/c that's software related....

SK

Thanks for all the help guys. I've had the side panel off with my home fan AND my 5 other fans running on full all day. It's still randomly shutting down. And by shutting down, I do mean it completely powers off without warning at seemingly random intervals. There is no reset. Like I said, I've been through heat problems with previous PC's... this just isn't the same. And yeah, I did mean Event Viewer hahaha. Sorry :P.

I'll see what I can do about the multimeter, and I'll take a look at the HSU today. While moving the motherboard out of the previous case, it may have been shifted or something so that could be it. If not... well, I'm thinking it's my power supply. The fact that the whole PC powers off even when the graphics card is idling is strange. Especially since I can sometimes be running a game like crysis with my card over-clocked for over an hour, but other times it will only run for moments before shutting down.

I'll get back with results in a while. Thanks again for helping me with this! It's been driving me crazy!

PS: This is my power supply if it helps any: http://ncix.com/products/index.php?s...Z%20Technology

It's the 700w model

Power totally shut off is due to bad PSU or a short some where. I have notice the fact that your mobo is a little of in fitting the new case, where likely the problem is. I would give it another chance before blame on the PSU. Try bench test first, which is carefully moving the mother board and all out of the case and set everything on top of newspapers on a bench to see if it help. If the power still shut off, then the PSU is the bad guy. Post back.