PC Won't Start

[shadrack]

Hi All,

This is on a ECS K7S5A.

I thought this was power supply but have tried a new one and still have the same problem. On pressing the power switch nothing happens. Well nearly nothing, the CPU fan kicks in for about half a second but no HD activity, no fan on the power supply. System is completely dead.

Can abyone suggest anything please?

Ta.
SR

 

[moody89]

This is the place to start looking:

http://www.tomshardware.co.uk/forum/261145-13-perform-steps-posting-boot-video-problems

I'm not sure if its in the guide or not but try swapping your memory sticks. Just leave one stick installed and try this in each and every slot on your board. If you're still not having any luck then try your next stick et. until you have tried every stick in every available slot. This eliminates the possibility of a bad RAM stick or a bad slot. If this doesn't solve your problem then your RAM is ok and you have another issue. You could try removing everything that isn't essential in your system. You only need RAM CPU and Motherboard to POST so everything else (even your GPU if you have onboard graphics) can be removed. If it boots with these removed then insert each component one at a time until you find your faulty one.

Try these as well as the steps in the guide linked to above and post back with any results. Best of luck!

 

[shadrack]

Ok, thanks. In the case of HDD's, CD's etc will just removing the power supply be sufficient or should I disconnect everthing?

 

[moody89]

Disconnect the power connection and the data connection to the motherboard. Bear in mind that with your HDDs removed, if your system does boot correctly then you will receive an error which states that the system doesn't know where to boot from. This is normal since you obviously have no bootable devices installed.

 

[shadrack]

Yes, fine with that. Thanks for the advice, will give it a try.
Regards.

 

[jsc]

Take the system back to bare minimum - motherboard, CPU & HSF, power supply, system speaker, and a way to turn it on. You should hear continuous long single beeps indicating no memory.

Silence indicates a bad PSU, motherboard, or CPU - in that order. Or it could be a short in the case somewhere.

In that case, remove all the components and breadboard
http://www.tomshardware.com/forum/262730-31-breadboarding
the motherboard, CPU & HSF, power supply, and system speaker

Most likely suspect is the PSU.

The best way to test is to replace the PSU with a known good one of similar power capacity. Brand new, out of the box, untested does not count as a known good PSU.

Next best thing is to get (or borrow) a digital multimeter and check the PSU.

Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.

http://www.youtube.com/watch?v=5FWXgQSokF4&feature=youtube_gdata

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU. You can carefully probe the pins from the back of the main power connector.

Motherboards and CPU's can only be tested by substitution.