computer won't start

shipcom

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Jan 19, 2008
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Got a Gigabyte GA-G33M-S2H with P4 HT 2.8 and 2GB memory.
Was working fine Tuesday - switched on Wednesday - not a beep.
Was advised by Gigabyte that it might be PSU.
New one installed - still same problem.
My USB mouse does light up - and components seem to get warm - but
nothing starts up (including PSU fan - but was told PSU would not work
unless everything else did - CPU, Mobo, Etc).
Been advised by shop I got PSU from that it might be mobo or PSU - but
I have no way of checking as do not own others.
After looking through your website - I tried with CPU out - but still no luck.
Anybody got any ideas?
Much appreciated .
Rgds
C
 

jsc

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Moderator
When ypu call for help on a problem like this, you need to post full system specs, in this case including the original and replacement PSU's. And the replacement PSU could be bad.

The following is extracted from one of my previous posts :

"Quick and dirty" under load PSU voltage checks (carefully, carefully) of the main outputs with DMM black lead grounded and red lead inserted into the back of the various PSU connector pins plugged into the motherboard:
yellow, yellow/black, and yellow/blue wires: +12 v
red: +5 volt
orange: +3.3 volts
All readings should be +- 5%.

While we are talking about PSU's, if you have a suspected bad PSU, also check the grey wire on pin 8. It provides a control signal called "PwrOK" that the CPU needs to start booting. With the PC off, it should be at 0 volts. It should go to around 5 volts (anything over 3.6 volts will be OK) within .5 seconds after pressing the power switch. You can have all the power outputs present. But if you don't have this, your PSU is broke and your PC won't boot.

After that, look at this:

http://www.tomswiki.com/page/Troubleshooting+a+New+Build

What you have is technically not a new build, but it may give you some ideas.
 

shipcom

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Jan 19, 2008
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Thanks your reply - sorry complete newbie to this.
Just got a very old computer from loft - and plugged in the psu
and it powered that mobo up fine.
So can't be the psu.
As advised by shop - probably mobo or cpu - but how do I check which ?

Rgds
C
 

shipcom

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Jan 19, 2008
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If I take the CPU out - and the mobo still does not power up with power switch prongs shorted - does that mean it's the mobo that's broken ?
Appreaciate any help
Rgds
C
 

williaml34t

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Jan 20, 2008
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Mobo sounds like a feasible cause. However, in 80% of cases it is something basic and fundamental like a loose power connector or cable somewhere. So it is worth checking and double checking these.

Often the most time and cost effective way to troubleshoot the motherboard is to just buy a cheap new (or working 2nd hand) one that matches your socket number.
 

notherdude

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Rebuild it barebones outside of case. Or at very least take out all RAM and cards and re-seat them, remove all drives, USB devices, etc.- try to boot with one stick of RAM only, then try the other stick -if none of this helps and you are sure it isn't the PSU, then MOBO is 95% the culprit - not CPU.
 

jsc

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Motherboard or CPU? The only way to check is by substitution. Here is where you need a computer savvy friend.

And we were all noobs at one time. Some of us just have a bigger headstart than others.
 

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