Question No power to keyboard or mouse

[That1GuySteve22]

I have been attempting to fix a PC and have been learning while I do it. The first problem I came to was when I plugged my HDMI into the GPU and it wouldn't display. Confused, I made sure all the cords were pushed in all the way and tried again but nothing changed. Finally trying to see if something would happen when I tried a USB keyboard or a PS/2 keyboard, I noticed they didn't light up as if the motherboard wasn't giving power. Any ideas that can help?

Edit: I have a Fatal1ty B450 Gaming K4 motherboard

 

[Kinora]

Is this a new build? What CPU? Any chance you are running a huge graphics card and a fast GPU? What's your power supply rating?

 

[That1GuySteve22]

Is this a new build? What CPU? Any chance you are running a huge graphics card and a fast GPU? What's your power supply rating?

It is not a a new build, a friend of mine said I could have it if I got it working (it worked for about 2 years). My CPU is a Ryzen 5 1600x, the PSU is a 750w, and I'm only using a EVGA GeForce GTX 780 so it should be more than enough.

 

[Kinora]

Well, I would guess that maybe a section of your power supply is bad. You could unplug the power connectors from the mother board and test them with a voltage meter to see if it's working correctly. Don't try it if you haven't any practical skills using a voltmeter; ask a handy friend with skills to check it out.

It's a place to start...

 

[That1GuySteve22]

Well, I would guess that maybe a section of your power supply is bad. You could unplug the power connectors from the mother board and test them with a voltage meter to see if it's working correctly. Don't try it if you haven't any practical skills using a voltmeter; ask a handy friend with skills to check it out.

It's a place to start...

I got the PSU to power an old computer just fine, though it definitely requires a lower wattage. I will see if the PSU is working tomorrow when I'm back at work.

 

[Karadjgne]

It worked as is for 2 years. What happened to make it stop working?

 

[That1GuySteve22]

It worked as is for 2 years. What happened to make it stop working?

He doesn't know, he just tried turning it on one morning and the screen wouldn't wake up (not the monitor or cord). He didn't change anything or let it overheat at all.

 

[That1GuySteve22]

Well, I would guess that maybe a section of your power supply is bad. You could unplug the power connectors from the mother board and test them with a voltage meter to see if it's working correctly. Don't try it if you haven't any practical skills using a voltmeter; ask a handy friend with skills to check it out.

It's a place to start...

I checked the voltage and it was all correct (12v, 5v, and 3.3v)

 

[Karadjgne]

Sorry if I was unclear, but Household electric. The stuff at the wall. You should be getting @ 115-125v or 220-250v (depending), and should not see a voltage change when a something like a hairdryer or oversized vacuum cleaner is plugged in and run. Should read the same with hot-neutral or hot-ground. If something is missing, or out of spec, it can affect the psu, which needs a certain range of AC power in order to change that to DC.

Many times you'll get correct voltages at rest, but due to bad plugs, loose connections etc, once you apply a good sized load, things get funky.

 

[That1GuySteve22]

Sorry if I was unclear, but Household electric. The stuff at the wall. You should be getting @ 115-125v or 220-250v (depending), and should not see a voltage change when a something like a hairdryer or oversized vacuum cleaner is plugged in and run. Should read the same with hot-neutral or hot-ground. If something is missing, or out of spec, it can affect the psu, which needs a certain range of AC power in order to change that to DC.

Many times you'll get correct voltages at rest, but due to bad plugs, loose connections etc, once you apply a good sized load, things get funky.

I don't think it is the power supply. I have used a backup one that I know works and tested the one from this computer on another PC and it worked fine for that one. I'm fairly sure the motherboard is dead because everything else (PSU, GPU, and HDD, everything besides the RAM, CPU, and MB) has been tested with a separate computer and still worked.