When I woke up today, my pc was off. I had left it on and it shouldn't have lost power, because it was connected to a ups. When I turned on the pc, it starts with high speed fans but no post. It then restarts and repeats. From the leds on the motherboard, I can see that it's switching between primary and secondary bios when it reboots. Switching from double to single bios causes pc to start with high speed fan, no post, and no reboot.
This isn't the first problem I've had with the system However. I don't remember when it started exactly, but at some point it started to ocassionally crash during exceptionally high load. Most of the time, it would simply freeze and a short bit of audio(~1 second or less)would repeat. Hard reset would be required.
Additionally, (and I don't know when this started happening either) sometimes the pc wouldn't boot right away. Fans would start up and spin at full speed, but no post. Sometimes, when this happened, restarting would work. Other times I would unplug the power supply and wait some time. I don't know if unplugging made any difference, but it's something I started doing. Sometimes the pc would start to boot correctly and then suddenly restart with full speed fans and no post.
These are the steps I've taken so far
The motherboard has a Debug LED display that shows a 2 digit code. I assume this LED displays something when it successfully posts, so this is mostly what I've been using to determine if it has posted. Additionally, I always have a display plugged in. At first, to the graphics card and then to the internal gpu.
I tried resetting the cmos and there was no change. I tried both bioses in either single or dual mode and there was no change.
I removed the graphics card, but there was no change. I unplugged everything from the psu except the two motherboard connectors. I tried using only one memory slot with either of my two memory cards and and there was no change..
This motherboard has leads for testing voltages, but I could find no voltages on most leads, while the pc was powered on. I found .01 on VRIN and 1.49 on VDIMM. The other leads are labeled VIOA, VSA, VAXG, VRING, VIOD, AND VCORE. I have not tested the leads on the atx connector directly. The motherboard is still in the case, which made getting the multimeter leads on the voltage measurement points a little difficult, but I'm pretty sure I was successful.
I tried a different power supply with 280 watts and single 4 pin 12v atx plug. (Previous power supply is 600 wats with 8 pin 12v atx plug, but this is the best alternative power supply I had available) there was no change. I did not test voltage leads with 280 watt psu.
Additionally I tried the 600 watt power supply in another computer computer, and that computer started up with high fan speeds and no post. Which has me stumped.
I had assumed that either the psu or the motherboard were bad, but now since the psu didn't work in both computers, and the motherboard didn't work with both power supplies, I'm just not entirely sure what steps to take next.
Specs and other info
The motherboard is a Gigabyte GA-Z87X-UD3H
. It's built with more durable components than average, such as solid state capacitors and beefy heat sinks. But still has only 3 of 5 eggs on newegg.
The power supply is a corsair cx600m.
It's unlikely to be an overheating issues, because I checked my temperatures religiously with speedfan for a while.
There was a storm yesterday, so it's possible there could have been lightening when I was asleep, but I think it's unlikely because I found no signs of damage on the motherboard, and no signs of damage with any other appliance in the house. edit: I checked and even though there was rain, I don't believe there was any thunder or lightening.
Any help is appreciated, and think you for reading.
Update: I got a new power supply and there was no change in the symptoms. I suspect the old cx600m power supply may have had some issue that damaged or corrupted the motheboard, because the cx600m exhibits these same symptoms in a known working computer:
sometimes the pc wouldn't boot right away. Fans would start up and spin at full speed, but no post. Sometimes, when this happened, restarting would work. Other times I would unplug the power supply and wait some time. I don't know if unplugging made any difference, but it's something I started doing.
Edited by FragmentalStew, 22 June 2018 - 06:24 AM.