Problem solving non-working desktop

Lifeforms

Yay for being the techie one in the family at the end of a phone! :rotfl:

Desktop computer, has Graphics card and sound card only card extension wise.
Not sure of overall specs, but essentially powers on, powers off immediately. Was powering on, powering off, then powering on, moving just a wee bit on to the Gigabyte logo, then powering off. Then cycles back to power on, then off, then on, then logo, then off etc.

All cards removed. HDD's seem fine (doesn't even get as far as checking those/memory etc anyway) Memory removed, and installed individually to check; no difference in any of these, so we're down to 3 components.

Motherboard, CPU, PSU.

We have just ordered a PSU as a replacement to try, seeing as it was my old PSU that got removed from mine (and possibly even a pre-computer/hack job etc) and used in mums when her old computer died (as a test to see if it were the PSU), then transferred over to new one.

MB, CPU, under 12 months old.
Basically we have ruled out anything else but those three parts, as nothing changes. CPU looks seated, fan working. Have suggested that Dad tries to re-seat it, but don't think he has any thermal paste/pads left, or alcohol wipes (bit awkward too as he can't see very well either) Offhand I believe he didn't use what was supplied, but used something better.

The PSU has a blue accent light, and does light up fine, but then we have these power cycles, so could be offending problem, but will know in a few days for definite, when we get another to try.

MB; shows no signs of burning, dry solders, smoke, flashy things, all jumpers present and correct, all plugged in etc.

Is there any way to test either the CPU/MB beyond actually replacing them? (with the computer not even running at all)
Unfortunately our spare parts have now dwindled, and we have nothing we can use in this computer. It's under 12 months anyway, with most parts bought from same company, so if the PSU doesn't solve it, then we'll contact those next, but we're at a loss. Previously we could just replace bits and see what was broken.
Has anyone had any problem with the same symptoms and can offer a suggestion?

* Nothing new installed, desktop had crashing issues few months back, but that was after a dodgy HP all in 1 was installed. Once removed, and cleared of it's HP crap, computers worked fine since.
Computer is shut down in the evening, and shut down went as normal; not cut off, not jammed, full shut down. Is plugged into a surge tower, but tower is then switched off after computer is turned off.

Jamie_Cortez

Sounds like the computer is shutting off to prevent damage as from your description its cycling the power to quick to even get to Bios for it to check RAM etc.

3 Things come to my mind.

1)Faulty PSU

2) Faulty RAM/RAM Slots Try different slots with different sticks (http://www.memtest.org/#downiso if you can get it to stay on long enough)

3) Faulty Motherboard.

You may if possible have to visit and to this yourself, but this is an excellent thread on combating this exact issue it covers everything.
http://www.tomshardware.co.uk/forum/261145-13-perform-steps-posting-boot-video-problems

Lifeforms

I can't get over for a couple of days, so stuck with what I can physically do myself. But then to be fair Dad is semi-techi, and built the computer originally, but as we've got no spare parts we can't check those out by simple case of replacing till we find the issue. He's done as much as I can do with it myself.

Almost all of those steps on that thread have been checked.

"Pull everything except the CPU and HSF. Boot. You should hear a series of long single beeps indicating memory problems. Silence here indicates, in probable order, a bad PSU, motherboard, or CPU - or a bad installation where something is shorting and shutting down the PSU.

Basically we don't even get to the beep stage, so can't use the manual and beeps to go further down the rule things out line.

Memory wise we've used both sticks one at a time in the appropriate slots, and makes no difference, so unless they're both broken, then they offer no solution to fixing it. Reasonably confident as much as we can be that they're fine however.

All components, aside the PSU and one slave HDD, are new. Two new HDD's, one providing the OS, the other for other junk, and I've just passed onto them a Sata dock, and IDE caddy to make sure the HDD's are not junked (Also to back up; ahem!) No indications, sounds, lights to indicate they're the problem.

I'm a little hesitant to allow my dad to poke wires with a multi metrer just yet! But that'll be an option to try later, for him after he's bought a spare PSU (as he has a desktop too, albeit it not parts interchangeable with mums). As through phone descriptions he's just realised that the PSU was the spare I lent him, to test the last but one desktop that died, and never got replaced for new.

If the PSU is not the issue, I'll try and look at breadboarding it and seeing if it's the case shorting somewhere. Case was a bit of an !!!! job (IMO!) so who knows

Jamie_Cortez

Heh if it was working before i can't see it being the case but then stranger things have happened....

Another option that i have seen work is try booting without the reset pins connected to the board, if the board has gone bad it could be a short on the pins that keeps it recycling.

Also if possible (you did say your dad had bad eyesight so maybe not him) take the CMOS out for 5/10 mins the put it back.

Lifeforms

We've reset the CMOS, and that now makes it just power on/power off. it lost that second power on, on for a second or two longer, then power off part of the original cycle (apparently!)

I'm going to suggest he tries to run it minus all memory, and see if he even gets any beeps/further just to make definite on the memory. After that, we'll just sit and wait for a new PSU to come, to try. Thank you for your help and suggestions though, it's been nice to be able to work out that they/I've tested it as much as we can.

Lifeforms

I know it's an old thread, but I wanted to update in case of someone searching it for a result in the far future!

After trying the PSU, no go. But we did manage to get it to a state of beeping to let us know what was us. All we could diagnose was a power problem. Nothing else in manual aside "power problem"

Packaged it up (CPU/heatsink onboard), and returned it back to the shop, who've tested it and concluded it was the mother board. Unfortunately they don't have the MB in stock any more, but after discussion they'll replace with another similar one, for an extra cost. Which despite my parents moaning at, I find acceptable as the MB itself was 9 months old. The new motherboard is a newer model, and was dearer anyway compared with the dead one.

Hopefully that will come back this weekend, and computer should be back together and working!