X51-R2, powers on for a second and then off

Question

Good Morning,

My daughter has an older X51 R2 - it's running a i3-4150, 16 gigs of ram, standard drive and GPU that came with it. She normally leaves the thing on 24/7 and plays games like Skyrim, etc. It's been a good machine for a long while and long out of warrenty.

Anywho recently she came downstairs and said "the computer doesn't work." I try to power the machine on and the fans spin and lights on the box come on for a second and then the machine dies. I have seen variants of this on Youtube where the machine goes into a loop trying to boot and then shutdown...then it tries to boot again, etc. In this case the machine does this once.

Having seen issues like this in the past my immediate thought was the power brick was flaking out. So I ordered a new one and nothing changed.

I then cracked the machine open and reseated everything. Nothing changed.

I started to remove individual parts. Trying to boot the machine at each stage. Nothing.

Finally all I had left in the machine was the CPU. Nothing.

I don't believe it's the power distribution board as when everything is plugged together the fans and drive are getting juice...if only for a second. That said...the problem could be there as well.

At this point I believe it's something on the motherboard or the CPU was finally baked too much. I had planned to upgrade the machine to an i5 but instead I'm leaning towards ordering an i3 just to see if that's the issue. If not then it's probably the mainboard that cooked (but I'm leaning towards the CPU at this point).

There's nothing on the motherboard that obviously points to a cooked component but with the component density I'm sure I overlooked something.

Any pointers on further diagnosing the issue?

Thank you.

Tesla1856 · Answer

@damosan wrote:

My daughter has an older X51 R2 - it's running a i3-4150, 16 gigs of ram, standard drive and GPU

1. She normally leaves the thing on 24/7 and plays games like Skyrim, etc. she came downstairs and said "the computer doesn't work."

2. I try to power the machine on and the fans spin and lights on the box come on for a second and then the machine dies. I have seen variants of this on Youtube where the machine goes into a loop trying to boot and then shutdown...then it tries to boot again, etc. In this case the machine does this once.

2a. I don't believe it's the power distribution board as when everything is plugged together the fans and drive are getting juice...if only for a second. That said...the problem could be there as well.

Having seen issues like this in the past my immediate thought was the power brick was flaking out. So I ordered a new one and nothing changed.

I then cracked the machine open and reseated everything. Nothing changed.

I started to remove individual parts. Trying to boot the machine at each stage. Nothing.

Finally all I had left in the machine was the CPU. Nothing.

3. I don't believe it's the power distribution board as when everything is plugged together the fans and drive are getting juice...if only for a second. That said...the problem could be there as well.

4. At this point I believe it's something on the motherboard

5. or the CPU but I'm leaning towards the CPU at this point).

1. Good story-telling imagery.

2. Yes, make it as minimal-config as possible. Your troubleshooting is good for someone who seems a bit new at fixing computers. I'm guessing you have other related training or experience.

2a. That doesn't really mean anything.

3. There is a proper way to test that combo "laptop like" power-supply system. You use a Digital PC Power-Supply Tester. What you have there is a AC-Adapter (DC SMPS) and a DC-to-DC Converter board.

4. Right. Well, the motherboard itself. Did you re-seat the ram DIMMs?

5. Not likely. If it's just been sitting in the MB all these years, 99% chance your Intel CPU is still good.

https://www.dell.com/community/Alienware-General-Read-Only/Alienware-Desktop-General-Hardware-Troubleshooting/m-p/5555517#M57436

All desktops should have a good UPS (like APC with AVR).

damosan · Answer

Alright - got a tester and ran both external bricks through it with the same results.

-12v = 14 (<-- this normal?)

+12v = 12.0

+12v2 = L.L (<-- this looks bad....)

3.3v = 3.2

5vSB = 4.9 - 5.0

5v = 4.9-5.0

pg= 0ms (<-- this looks bad...)

damosan · Answer

(As an aside) CMOS battery -- if it's stone dead will that cause problems in these rigs?

damosan · Answer

Update: I ordered a new daughter board (the DC-DC converter) and swapped out the old one. The machine is up and running again. D.

Tesla1856 · Answer

@damosan wrote:Update: I ordered a new daughter board (the DC-DC converter) and swapped out the old one. The machine is up and running again. D. Good work. :Yes: Yes, those incorrect power-supply output voltages (and no PG) indicated a bad PS system. Yes, CMOS battery must be good.

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X51-R2, powers on for a second and then off

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