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Solve : Dead PC - next diagnostic steps suggestions please?

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I hope someone can help me.

My computer went kaput on Friday evening.  I was watching the TV and heard it getting a bit loud so went to have a look.  It seems my water cooling reservoir had sprung a leak and very little liquid was flowing.  I switched it off immediately (mistake #1) and opened the box, but no liquid had spilled inside.  The reservoir is outside, so in that respect I was lucky.

I plugged her back in and nothing.  Completely dead.  Not even a PSU fan.  Found the PSU supplier website and it suggested shorting a couple of pins to check whether the PSU was the problem.  I shorted them and the PSU kicked into life.  I also had a fiddle with the connectors and as soon as I unplugged and replugged the 4-pin ATX connecter it started up, but the PC was still dead other than that - it refused to POST.

Bought a new motherboard and swapped that in.  The PC basically dead still.  So this time I thought maybe it was more than just the motherboard connector and that there may simply just be not enough power getting through.  ESPECIALLY since the new board had a small LED that allowed me to see that power was coming through, but which blinked on and off when I tried switching the PC on.

So, one new power supply later I am now getting a long beep followed by 3 short ones.  It's an AMI Bios so that means memory problems.

Took out all the memory and, because this new board accepts single sticks I tried them all one at a time, and even tried a stick that I had laying around but which had not been in the PC previously.  Every time 1 beep followed by 3 short ones.

Additionally, the PC will not output to video, even for the POST.

My concerns are that I could change all the RAM for a whole load of cash but it is also possible that I fried the CPU and, since it is an AMD with onboard memory controller, that might cause the same POST error as bad RAM.  Other than the one spare stick I had, I have no other RAM or spare CPU to switch in.

MY question is: what should I do next?  I think I need to just buy a new CPU, although it is possible I also fried the GPU.  Again, no spare PCi-E cards to try.  Could the CPU be OK, but the problem be caused by the GPU?

Specs:
AMD Athlon 64 4200 X2
Gigabyte K8N Pro-SLi (the old one)
Asus A8N32-SLi Deluxe (new one)
2Gb RAM 400DDR (2 x Kingston matched plus 2x Corsair value matched)
Seasonic S12 500w PSU (Old one)
Jeantech 600w Modular PSU (new one)
XFX nVidia 7800GT PCi-E graphics
Creative X-Fi ExtremeGamer sound

Any suggestions gratefully received.The LED onboard should not be blinking...that board could possibly be bad.

I would try this:

Remove the MBoard from the case. Place it on a piece of foam rubber or CARDBOARD.
Hook up the PSU, one stick of RAM in the slot closest to the CPU, the vid card and a keyboard and mouse.
Power up and cross your fingers...
If it boots properly congrats you have found your problem...the MBoard was shorting on the case. Carefully re-install it using the standoffs provided. These can also be bought at a computer store.

If this method fails the next thing to try would be another known working video card. Borrow one for a day since we don't want to spend money yet.

Lastly do the same with the RAM.

If all the above produces the same results then the MBoard is DOA...do an RMA on it.

Best of Luck.

patio.   8-)Water cooling and electronics. I never did get that one.   Quote

Water cooling and electronics. I never did get that one.  

I use MCT-5, a NON conductive fluid.  It still makes a sticky mess over all the components if it were to ever get on them, but shouldn't short anything.

Patio:

I've just re-read my post and think I've probably misled you.  The new board, when frst fitted, had a blinking LED.  I took this to be a problem with the PSU even though I had previously shorted it and found it working.  I thought maybe there were just deficiencies.  With the new PSU fitted, the LED is steady green, the PSU fan powers up, and the whole thing gives me a POST test but no video.  I therefore believe the Mobo is fine (it is on spacers anyway, unchanged from the fitting of the previous Gigabyte board.

The only key components I have not yet changes are the CPU, RAM and Graphics.  I don't know anyone else who has a pci-e card that they can lend me.  Would a pci one suffice just to prove a point?  The RAM I believe is fine because the replacement stick I used gave me the same result.  I could try putting together an old system I cannibalised a while back and see if they work in that(?) if you think the RAM might still be a problem.

I suppose the thing I'm most bothered about is the possibility of buying a new CPU only to find out that it is really the GPU.  If the computer ought to be giving me video (bios screen) even with a dead CPU, this would be useful information to me.A dead video card can cause a computer to boot to a black screen or not boot at all.
My 7600gs died and caused just that, I removed the card from the motherboard during troubleshooting and like magic the computer would boot without problems.
I returned the card for warranty and got by with the motherboards integrated graphics for for 2weeks while I waited for the new card.

Just try removing the card altogether and see if she will startup.OK, I've asked my IT department at work to see if they can dig out an old PCI graphics card for me.

I'm still concerned that the consistent POST error (AMI bios and 1 long 3 short beeps) says memory but no bios screen says GPU so I'll give that a try.

Thanks for the hint.Ok so I tried a RATHER old PCI card (it was a TNT Pro with DVI output - no idea who manufactured it) and it worked!

I did have a further problem with the system not recognising my keyboard but I used a diagnostic method suggested on the Asus forums (Basically, remove everything and try hitting 'delete' at boot and keep adding things until you work out what's preventing you from doing it)

So now I think it might be best for me to get myself a nice new GPU card and go with that.  In theory, I suppose there could be an issue with the PCI-E slots on the new Mobo but I'm hoping that's not the case...

I'd like to thank those who responded to my enquiry here and hope that I've written enough about the resolution that it might be helpful to others.  Dead PC might=dead gpu only.  Madness, isn't it?Glad you got it sorted...UNFORTUNATELY the only way to test that PCI-E slot is with a known good card...Ok an update.

The GPU is fine.  I have no idea why or how, but it now works.  It really did not work at all while I was posting here and has refused to work once since.  But it does, generally, work.  It's likely that I have not completely fried it but created a glitch somewhere so may yet need replacement.

I found out because I was about to remove it from the water system and just thought 'one more go' and plugged it back in.  I'm glad I did.

Now I seem to have developed a hard drive problem, but I can deal with that...


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