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PC Randomly powers off

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October 19, 2010 1:07:56 AM

OK, my PC has started to randomly power off. Sometimes I'll click to open a file, like a PDF, and BAM, it simply shuts off. Another time I was burning a CD.... the first few minutes went fine. Then when I checked back the PC was off. There have been other times, but they are similar. I click something, or it's under load, and without warning it shuts off.

Originally I was thinking it was a memory failure issue. I ran the Windows 7 memory checker. Oh, wait, should I give my specs now?

ASUS P5N-D Motherboard
Intel Core 2 Quad Q955o/2.83 Ghz
4 Gigs RAM (DDR2/400Mhz)
420 watt power supply
Windows 7 64-bit
500 Gb HDD
GeForce 8600GT 512Mb video card
Theres a big fan on the CPU, and another one below it, and a small one on the video card. One exhaust fan out the back. An open vent on the side. It seems to be more stable with the side off, which might be my imagination because I still have the problem even then... it just doesn't seem so bad. Oh, and if I power it one right after it powers off, it will usually power itself back off fairly soon if not right away. Waiting a bit helps. Which is why I think it's temp related. But I've had this set up for a year and a half with no problems until now, so I think something is failing.... somewhere.

Ok, anything else? So the memory checker said no problems. Then I thought maybe something is overheating. Using SpeedFan 4.41 I monitored the temps... generally speaking they hover around: temp 1 = 47C / temp 2=40C / the CORE temps are around 50, sometimes 51, but not higher - usually 48/49C. I read another post that said up to 60C is OK, so now I'm thinking it's not that.

TROUBLESHOOTING SO FAR: I took out 2 of my four memory chips - still have the problem. I replaced them and took out the other two. Still had the problem. I unplugged the DVD burner. Still had the problem. I removed the CPU cooling fan, blew it out, replaced it. (it had some grey looking paste on the CPU... thremal grease? wax? not sure what it is or how best to clean it and replace it... suggestions??)

I want to take out the video card and see if that's it, but I dont have a spare... how do I know which part is failing? CPU? Motherboard? Power Supply? My buddy says I should dump it and get a Mac, but I'm not ready to throw out what has been an otherwise great system for me, and I don't want to buy all new components if I can figure out what part is broken and just replace that.

Any suggestions would be greatly appreciated!

More about : randomly powers

a c 105 à CPUs
October 19, 2010 1:11:50 AM

any issues playing games?
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a b à CPUs
October 19, 2010 4:28:01 AM

Even at low load, your system crashes. First, I'd use only one RAM module instead of two at a time to check whether it's a memory issue or not.That will narrow down the suspicion by a module at a time.

Second, I would check the PSU if I were you. 1.5 years is a common age for an "unbranded" PSU to start dying. Since you didn't mention the PSU brand, I assume it comes with the case.

If you can test the setup with a working PSU, that would be very helpful. I also would like to advise you not to turn on the PC after knowing it's intermittently shuts down by itself. It's unhealthy for the other components.

Hope this helps!
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October 19, 2010 4:47:12 AM

i've had the same problem as you. and i rekon its the psu. it eventually stopped working altogether. the symptoms were similar to yours at the beginning though. just try and look at any frayed wires that might have created a short. a better indicator that it is your psu is the random crashes that you computer may experience.it indicated that your cpu did not get the required volts and froze.
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October 19, 2010 4:49:36 AM

^+1 For the first hand experience. :D 
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October 19, 2010 4:56:56 AM

haha i do think its your psu. theres no way your hardware could survive on a no name 420 w psu. the hardware you have is quite power hungry. my psu has also a no name psu. peak power of 500w. after ocing and using it for 2 months it died and i had to get a new psu. not to worry though i believe your hardware will remain unscathed
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October 19, 2010 5:00:51 AM

damasvara said:
^+1 For the first hand experience. :D 

thanks :D 
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October 19, 2010 5:33:32 AM

Cool, thank you for the advice. I'll try the RAM one at a time, but I've read other websites that talk in general terms about power supply units failing. The psu (I'm a little out of my element here... I know just enough about the innards of the computer to get myself into trouble, but not enough to get out of it!) I have is a "Turbolink ATX-CW420W". I've replaced memory and drives before but not a psu. Is it as simple as unplugging everything, unscrewing it from the case, and then replacing it in reverse - screw it in and plug it in? Given my components, any recommendations on how big a unit to get? (My PC was bought from a built-to-order site, and I do remember skimping on the psu thinking it wasn't very important)

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October 19, 2010 5:44:46 AM

bryann816a said:
not to worry though i believe your hardware will remain unscathed

I won't be so sure about that. I've had the same issue myself. Fortunately for me, and you, the other components are unaffected. But for some people out there, they got the short straw. HDDs are the most commonly affected. With the GPU and motherboard next on the list. That's why I advise the OP to hibernate the PC usage until he can find a test PSU for comparison. It would be a pain if he were to change the other components just because of a crappy PSU. :fou: 
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October 19, 2010 5:56:46 AM

fatdawg said:
Cool, thank you for the advice. I'll try the RAM one at a time, but I've read other websites that talk in general terms about power supply units failing. The psu (I'm a little out of my element here... I know just enough about the innards of the computer to get myself into trouble, but not enough to get out of it!) I have is a "Turbolink ATX-CW420W". I've replaced memory and drives before but not a psu. Is it as simple as unplugging everything, unscrewing it from the case, and then replacing it in reverse - screw it in and plug it in? Given my components, any recommendations on how big a unit to get? (My PC was bought from a built-to-order site, and I do remember skimping on the psu thinking it wasn't very important)

Now that it's narrowed down to the PSU, you can rule out the RAM module check, since it might risk your whole system. I'd suggest to suspend the PC before you can get at least a test PSU.

This is the most common mistake PC users do: Underestimating the importance of a PSU quality. Let's visualize a future condition where your PC can't boot at all because the current PSU have died. After you replace the PSU with a, let's say, a brand new Corsair brand, but the PC still won't boot. That's when you know you're too late. You wouldn't wanna go through that, now would you? :non: 

IMO, a $50-60 investment on the PSU to save your, say, a $500 PC is worth every penny of it. Or would you like to add another $50 for a broken HDD? I, for one, wouldn't. :p 
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October 19, 2010 6:01:56 AM

Yeah, I see the importance now... only as strong as the weakest link, etc etc. As I was looking at psu's on newegg the PC.... you guessed it.... powered off again. :( 

I pulled out my old old PC tower from before this PC and it still has a psu in it... it is only 350W though (Tiger Direct brand? Tiger something...) I thought maybe I could just swap it to test the theory? But maybe it doesn't have enough juice for this configuration.

I'll poke around on newegg... still would like to know what specs to look for in a psu though.... watts? brand?
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October 19, 2010 6:14:56 AM

fatdawg said:
Yeah, I see the importance now... only as strong as the weakest link, etc etc. As I was looking at psu's on newegg the PC.... you guessed it.... powered off again. :( 

I pulled out my old old PC tower from before this PC and it still has a psu in it... it is only 350W though (Tiger Direct brand? Tiger something...) I thought maybe I could just swap it to test the theory? But maybe it doesn't have enough juice for this configuration.

I'll poke around on newegg... still would like to know what specs to look for in a psu though.... watts? brand?

Another unbranded PSU with a lower wattage is not a very good idea. And I thought I advise you not to use the PC before you can get a the replacement PSU. But if you still insist, it's your property anyway. Suggestions are all we can give you here.

Just as Dipankar said, a Corsair or CM with 500W power should be enough for your current configuration. I personally use a 400W PSU with 80+ efficiency and active PFC. The latter two features are common in a good quality PSU. I have no experience with high-end brands though, since my rig is an undervolted "Green" one, a simple mid-class PSU from Sirfa (the name's kinda like alien IMO :lol:  ) is more than enough for me. But clearly, for your setup, a better assurance is needed.

EDIT: Grammatical error...
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October 19, 2010 8:12:40 AM

There are products not listed on the net which has an 80+ efficiency and an active PFC. Even If you don't overclocked this PSU it makes a big difference using them, I highly recommend them.
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October 19, 2010 8:23:08 AM

I'm too late aye? Yeah it's the PSU. I'm 100% positive. Even if it's brand new, 420W is just-enough-to-be-fit-into.
When you buy a PSU you need to have a slightly higher than required power, in order to stay safe. For ex, if your system is like that I recommend 500W PSU, although the required power is maybe ~ 400W. Also old psu tend to give less efficiency output.
The PSU is just overloaded to give bigger power than it can. It collapses by itself.
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October 19, 2010 3:29:57 PM

Its most lokely going to be the PSU like everyone else says. I had a cheap no name PSU and it blew out my motherboard when it died. Needless to say that wasnt cheap.
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October 19, 2010 3:45:48 PM

damasvara said:
Another unbranded PSU with a lower wattage is not a very good idea. And I thought I advise you not to use the PC before you can get a the replacement PSU. But if you still insist, it's your property anyway. Suggestions are all we can give you here.

Just as Dipankar said, a Corsair or CM with 500W power should be enough for your current configuration. I personally use a 400W PSU with 80+ efficiency and active PFC. The latter two features are common in a good quality PSU. I have no experience with high-end brands though, since my rig is an undervolted "Green" one, a simple mid-class PSU from Sirfa (the name's kinda like alien IMO :lol:  ) is more than enough for me. But clearly, for your setup, a better assurance is needed.

EDIT: Grammatical error...



Thank you for the recommendation.... I would love to be able to not use the PC.... but I need to check the forum to get the advice... kind of a catch 22. The good news is I will be going to Frys to look for this or something similar in the hopes that I can get it today, and fix it today, rather than wait another day for shipping. But if I can't find something with these specs - the 80+, PFC, high wattage, brand name - then I'll wait for newegg... It's not at all a bad price - way better than shelling out the money for a whole new system.

When I looked at the recommended product from newegg, I noticed the fan looks lie it is on the bottom of the psu? My current set up has a fan blowing out the back... so this will vent "down" into the case? Perhaps I will invest in quality 80mm fan to vent the case... Because of the large CPU heatsink/fan, I can't put a fan on the side vent. But it looks like I can only fit an 80mm fan out the back.

I really do appreciate the advice... and no, I'm not going to try the other psu from my old system.
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October 19, 2010 8:05:25 PM

Ok... I went to Fry's and picked up a new PSU... I ended up getting the one recommended earlier - the Cooler Master Silent Pro M700W - probably overkill but better than underkill.

The good news - I was able to get it today and don't have to pay for, or wait for, shipping.

The bad news - I have to send in a $30 rebate to make it the same price as newegg... but I'd rather wait for that than the product.

Installation went smoothly and it is running now. It's only been about 10 minutes, so I'll have to wait and see if it fixes the problem.

I got a new case fan, but will return it. I thought I could only put in an 80mm fan, but now I see holes for a 92x92 fan.

I also saw fans at Fry's that are "flat" and vent through the PCI slots in the back of the case. Has anyone used a fan like this? Is it effective? I have the room for something like that so I will consider it. Perhaps I'll go with 2 - one square 92x92 up top and one of those on bottom.

Thanks again for all the posts... I really didn't want to shell out $700+ for a new system.
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October 20, 2010 1:04:29 AM

your welcome lol btw the fans are good if your cable management if decent. with out good airflow the fans are redundant. always remember intake fans from the bottom exhaust fans on the top of the case :) 
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October 20, 2010 1:14:03 AM

the pci coolers were probably for cooling hot graphics card. even so i doubt if its efficient enough to cool your card down significantly. i had one of those pci coolers that cost 45$ and it only cooled my card down by a couple of degrees :)  i'd invest in my intake and exhaust fans though. good airflow reduces overall temps in your system remember alway minimise cable clutter its amazing how significant the improvements are :D  have fun with your new project :) 
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a b à CPUs
October 20, 2010 3:06:39 AM

fatdawg said:
Ok... I went to Fry's and picked up a new PSU... I ended up getting the one recommended earlier - the Cooler Master Silent Pro M700W - probably overkill but better than underkill.

The good news - I was able to get it today and don't have to pay for, or wait for, shipping.

The bad news - I have to send in a $30 rebate to make it the same price as newegg... but I'd rather wait for that than the product.

Installation went smoothly and it is running now. It's only been about 10 minutes, so I'll have to wait and see if it fixes the problem.

Thanks again for all the posts... I really didn't want to shell out $700+ for a new system.

Seems to me, you've sorted out the issue there. Glad to hear that!
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October 20, 2010 6:23:52 PM

Good news so far... after leaving the computer on all day, and multi-tasking (check email, work on docs, rip movie, re-code movie, all at the same time) the computer hasn't shut down yet.

A big thanks for the info and recommendations!

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October 20, 2010 6:28:25 PM

Anytime... Glad to help! :) 
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October 27, 2010 12:03:41 AM

Best answer selected by fatdawg.
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!