Computer not booting


Novice Member
My new PC which i have custom built is not booting with the case side on, i have checked that the case is not trapping anything and it isnt. I have not got the case light connected and it still only boots with the side off.

I have decided that the only possible thing must be cooling but the air from the heatsink is cool and when i open the case there is no noticeable heat. This started happening around 40mins ago.

Any advice is very gratefully recieved.

Monty Burns

Well-known Member
Is there anyway (unlikely I know but you have an unlikely error!) that putting the case on could cause the mobo or a.n.other wire connection to be touching metal where its not supposed to be?

I once had a situation where I had not used all the screw points putting in a mobo and, because of this I guess one of the strips/lanes of the mobo was touching metal case where it was not supposed to. This caused it not to boot. I put all the screws in and it was fine.

Just an idea thrown in the air....

Good luck!


Novice Member
Thanks for the reply, i am very puzzled now as my computer now works with the case on. I will see how it goes, i have done a virus scan and i am virus free


Novice Member
It does sound construction related. maybe next time you open the case and put it back on it won't work...
You are not forcing anything are you ? ?


Novice Member
No nothing, it all fits fine, nothing is being blocked and the screws are tightened but not too tight.


no, please dont....

unless you are using a dual core cpu, then a 20 pin psu is adequate for a 24pin motherboard. The normal p4 yellow/black 4 pin connector is "integrated" when using a 24 pin psu.

so, a 24pin connector=a 20pin connector+the yellow/black 4 pin connector. Clear so far?

the yellow/black (hereafter referred to as atx12v) connector should be a seperate 12v rail from the 20 pin connector. So that the cpu gets it's own clean stable 12v to regulate. If you use a 20pin-->24pin convertor, you end up splitting the 12v from the psu that runs the drives+mobo and using that to run the cpu and some parts of the motherboard from. Which can probably overstress the 12v rail.

From intel's own docs, use a 24pin psu if you have one, if not, then use a 20pin psu and connect the atx12v 4 pin connector too to compensate. Some 955 board even have a standard molex connector on the motherboard to compensate for 12v power (intel 955xbk springs to mind)

Short story, using a 20pin to 24pin adapter *may* cause a psu overload, which could damage the mb/psu/cpu depending on your particular psu limits.


Novice Member
Which motherboard are you using? DFI's sometimes have a problem when not used with a 24pin PSU. This isn't to say don't do what Werner has suggested.


Novice Member
Added firewire card today and guess what, it wouldnt boot at all but the fans were spinning. I looked on t'internet on another computer and found someone with a similar problem and the graphics card was faulty. So i removed my graphics card and the computer started booting properly (i could tell because the keyboard lights flashed). I then re-fitted the graphics card and it works still. I will see if i have any more problems and if i do i will exchange the graphics card

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