Why is my PC dead? Motherboard, CPU or other?

MGudgin

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Jan 27, 2015
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Last year I built my first PC and for ten months it has worked flawlessly. One week ago the PC wouldn't fully start - fans and lights would turn on, but nothing else. Copious research suggested this was the power supply (at the time a Corsair CX600M) so I ordered a PSU tester to confirm, which it did. Based on numerous reviews and articles I then ordered an XFX Pro650w, installed it... and now nothing at all. If I press the power switch the fans twitch and nothing else. I've tested this power supply as well to make sure I wasn't sold a dud, it passes with flying colours. I've confirmed every connection, checked that everything that is supposed to be in is and is seated properly.

I've tried removing all peripherals and cards, no activity, tried rebooting with just one stick of RAM, swapping that stick, still no activity.

I fully admit I'm no expert (like I said this is my first system build) so glaring errors are not out of the picture. That said, this system worked perfectly for the better part of a year without a hint of trouble.

I'm now thinking its the motherboard, but it has also been suggested that its the CPU (though it was also suggested by other sources that this is unlikely).

My system at the moment:

ASUS M5A99X Evo R2.0 motherboard
AMD FX-8350 processor w/ stock cooler
16Gb 1600MHz RAM (2x8Gb DIMMs)
128Gb SanDisk SSD
MSI NVidia GT 630 (this is being upgraded to an ASUS GTX 750Ti the moment the system's operational)
TP-Link wireless card
2Tb Seagate Barracuda HDD
Samsung optical drive
Sharkoon T9 case

Hope you can help, I'm currently using a 5 yr old ultra-budget laptop that's only slightly better than a paperweight.
 
Solution
There are a few possibilities here and motherboard is one, although the more common issue would be the PSU (a new PSU does not necessarily mean a working PSU - even the SeaSonic built XFX Pro's can have a bad one now and again). I will suggest breadboarding and working parts in until the PC no longer boots. Or see if it boots at all with only CPU (with heatsink) ram and motherboard speaker (to get the POST beep)
Look over the motherboard concentrating around the VRM area for any swollen or leaky capacitors or any blown IC's

MGudgin

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Jan 27, 2015
4
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4,510


Just got back from work and tried that, no joy I'm afraid - still completely dead.
 
There are a few possibilities here and motherboard is one, although the more common issue would be the PSU (a new PSU does not necessarily mean a working PSU - even the SeaSonic built XFX Pro's can have a bad one now and again). I will suggest breadboarding and working parts in until the PC no longer boots. Or see if it boots at all with only CPU (with heatsink) ram and motherboard speaker (to get the POST beep)
Look over the motherboard concentrating around the VRM area for any swollen or leaky capacitors or any blown IC's
 
Solution

MGudgin

Reputable
Jan 27, 2015
4
0
4,510


Fairly sure it's not the PSU as I've already tested it with a PSU tester, but those things probably aren't infallible so I'll definitely test it again. Won't have enough time to safely breadboard the PC until the weekend but a preliminary look doesn't seem to reveal any damaged capacitors or other obvious signs of damage. I'll report back later once I've had a chance to do all of this properly though.

UPDATE: I have now breadboarded the PC which allowed me to trace the problem back to a fault internal power cable - the new PSU itself is fine but at least one of the cables shipped with it wasn't working properly (I do wonder why the PSU tester didn't register a fault in that case). Switched to the cables from the old PSU and hey presto, one working PC. Thanks for your time and assistance.