Help with troubleshooting PC hardware
Hello Tilderonians,
I have inherited a non-functional ~10 year old gaming PC that was previously used as a VR rig for kids. The people who owned said PC had no info on how or why or how long it had not been working for.
I got it home, plugged it in, and tried to power it on. Nothing happened.
I opened it up. With the PSU switched on, there is a red led lit up on the motherboard, an ASUS Pro Gaming Z170i. According to the user manual, this just means the mobo has power and is in standby. There is also a white led lit up on the gpu (a GTX1080) which seems to also indicate simply that it has power.
I first assumed that the power button built into the case was the issue. I found where it plugged into the mobo and, on advice from the internet, used a screwdriver to jump the pins for the power switch. Nothing happened.
I then also read online that the PSU fan should spin up when turning it on with nothing plugged in. So I unplugged everything and tried it and nothing happened. I read the LEDs on the hardware could still function even if the PSU was dead, so I decided that was the issue. I ordered a new PSU, same 750 watts. Old one out, new one in, turned it on and again...nothing happened. The fan didn't spin up on the new PSU either. The same LEDs as before came on the mobo and gpu but nothing else.
At one point I also swapped the single RAM stick with another I had that I knew worked, but that didn't change anything.
At this point I don't know what to do. Is there a way to test the motherboard? What else could stop the PC from doing anything at all? I've never built a PC before but I've installed/swapped several parts.
I don't want to spend a ton of money to revive this 10 year old hardware but I was willing to drop ~$60 on a PSU. Please let me know if you have any ideas.
Thanks for reading.
You can't really test whether a PSU is good just by plugging it in without having it connected to something. You have to short (edit: TWO VERY SPECIFIC PINS!) in the ATX 24-pin connector so the PSU thinks it's actually connected to something. They sell bridged testers for it, but you can just use a length of paperclip to bridge the pins.
I'm sorry that I can't remember which number pins those are offhand; I have a full tester for that task that tells me voltages and whatnot, so I've always just looked it up when I needed to.Edit: they are pins 16 & 17. Consult an ATX 20+4-pin header pinout chart to identify the correct ones.That's kind of irrelevant at this point though, since you already got a new PSU.
You've already got a hunch that the problem is something to do with the startup signal. Those two pins the power button shorts to send the startup signal should read 3.3V when you bridge them with a multimeter set to DC voltage mode (though a few boards will push 1.5V instead). If the power button pins read the correct voltage, you check the super-IO pins to see if it's receiving the startup signal as well. Maintain the short across the power button pins and test each of the pins on the super-IO until you find that same signal. If none of the pins show the signal, then you've got a broken trace from the power button header.
Most likely you'll find the signal though, and probably a few other signals besides. Your next thing is to check all the capacitors to make sure they have continuity. The most likely problem is that you have a blown capacitor somewhere in the VRM (the ranks of barrel capacitors that ring the CPU socket). You can replace them with just a soldering iron and braid, but a desoldering gun will make the job much easier. Look up "through-hole capacitor desoldering" or something similar to find videos to show you how it's done.
(Edited because it occurred to me that I could've been construed as advising someone to bridge any random two pins on a 700W power supply, which would definitely lead to at least an unpleasant shock and maybe worse. The correct pins are 16 and 17.)
Could you perhaps share a photo of the innards? (or more)
Are all the plugs inserted properly, flush and in their right places? Especially power plugs?
Is... is there a CPU on the motherboard? There are a bunch of debug LEDs on this board, are you sure nothing else is lit?
Apologies, I'm currently at work and don't have the machine in front of me. The only pictures I have are what I took of the connections I needed to make when replacing the PSU, so probably not super helpful but here they are.
https://ibb.co/8nr1rpvq
https://ibb.co/R4j2htLQ
https://ibb.co/DH7cxDzM
https://ibb.co/YFfPP669
There is a CPU on the motherboard of course but I'm not certain what exactly as I never took the fan off.
I did read about the indicator lights in the mobo manual and so I believe I located them all and none were lit up when the machine was powered.
I do believe everything is plugged in properly, as no one else would have opened it up before me and I replaced the PSU and was able to confirm power to the mobo and gpu via the LEDs.
Thank you for the pics, that looks fine. You should probably refer to promonk's advice next.
If the machine has on-board video try removing the GPU and test with just that. If not, try another GPU. It's possible it's instantly shutting down if it's detecting a fault there.
Whoops, sorry, I did try this I just forgot to mention it. Well, half of it anyway. I don't have another GPU to test. Good suggestion though.
And you're sure the power outlet you're using is good? Amazing how many times simple things trip us up.
Also make sure you're waiting at least 30 seconds. Some startups take awhile if hardware has changed or monitor hasn't fully booted up.
I wouldn't suspect your RAM, that would be an error you could identify once you've hit POST. Have you tried booting with bare minimum peripherals? (No GPU or other PCI cards, one stick of RAM, no USB headers, drives, etc)
I sort of half-assed this and didn't unplug everything, just the GPU and hard drives. I'll have to give it another go.
You should (theoretically) be able to pull the RAM, even. You should be able to just boot with the motherboard, PSU, and CPU. You'll get POST errors about no RAM being found, but at that point, at least you know you're POST'ing. But if your PSU isn't even spinning up, it sounds like some kind of failure to initiate the boot/POST sequence. When you jumped the power button, did you do so on the motherboard jumpers?
Are you trusting the board was wired correctly to start with? Or did you consult the manual to figure out which pins to short?
It could be someone else worked on this and didn't hook up the front panel properly
I consulted the manual but also the labels were printed on the board, if extremely small.
Did some internet trawling. Very surprised there is no troubleshooting table in the manual. That used to be standard. (Waves cane at clouds)
Anyway, bases on the linked posts below, my suggestion is to try shorting the cmos reset pins (see section 1.7 of the manual), then wait 4 minutes and see if it will boot. While you are at it, you could replace the cmos battery. If you can get it to boot to bios, see what version the firmware is at, and see if you can update it. The second post I linked is from 6 onths ago and doesnsughst that the later bios versions fixed some problems.
If that doesn't work, you might also try with just one stick of ram and see if that makes any difference.
https://www.reddit.com/r/buildapc/comments/3wi6kb/comment/cz1s0mm/?utm_source=share&utm_medium=mweb3x&utm_name=mweb3xcss&utm_term=2&utm_content=share_button
https://www.reddit.com/r/buildapc/comments/3z4j4n/comment/oe7bl45/?utm_source=share&utm_medium=mweb3x&utm_name=mweb3xcss&utm_term=2&utm_content=share_button
Good luck!