how to test psu voltages with multimeter when all cables are black!?

[reg66]

as per the title really, i need to test my EVGA 850 G2 with a multi-meter to check all rails are performing as they should. however, all my cables/wires are black! anyone know if/how this can be done? thanks

BTW my pc boots, runs, for the most part so it's not dead completely - just need to check voltages

some history:
recently my usb ports have started failing along with the onboard bluetooth (Asus Z370-G Gaming Wifi), only the USB 3.1 ports work, with only one device connected - more than one and both stop working. also, i'm getting random blue screens (have tried fresh installs, driver updates etc etc, along with a fail to boot LED on mobo the other day (BOOT_DEVICE_LED), so initially i thought it to be my EVO 960 NVME gone belly up (have tried other ssd's and both re-cloned / reinstalled the 960, all works fine now). i'm not sure if this is due to mobo failing or PSU. strange thing is that when i plug a tiny 500mb USB stick in to USB 2.0 or 3.0 ports, it's read fine. any thing larger and more demanding, such as external hdd or even logitech receiver and i just get 'device not recognised'.

any help/anyone able to shed any light on this matter?

cheers

 

[Peter Martin]

It sounds like hardware issues. Motherboard. If it’s booting and running then it’s probably not the power supply.

Give us your system specs especially the power supply

 

[RememberThe5th]

check for pinout on google and care for notch. Worst case psu shorts out and cuts off power or multimeter fries.

 

[reg66]

It sounds like hardware issues. Motherboard. If it’s booting and running then it’s probably not the power supply

that's my thinking, but my corsair air 240 case with aio twin fan cooler and strix gtx 1080 was a PITA to put together, don't want to have to RMA the mobo unless i have to, hence, can i check the PSU voltages first with a multi meter. thanks for the response tho, i'll see if anyone can shed any light on this


sorry, specs are;
PSU: EVGA 850W G2
CPU: i7 8700K not overclocked
32GB G.skill RGB RAM
MOBO: Asus Z370 G Gaming Wifi

 

[reg66]

while looking up 24 pin out images i found a 'power supply tester' for 20/24 pin atx supplies (plus molex tester) that looks most useful and what i need. a decent digital one costs about £10 on ebay. might help others. this is what i got:
digiflex atx power supply tester

you can probably find cheaper for the same thing from china/HK but i'm in rush!!

 

[reg66]

just to add, i've doing some pretty intensive stuff on my pc that had all the cooling running away at full pelt, i'm wondering if the southbridge has gotten too hot and started to fail.

 

[RememberThe5th]

Those testers are not designed to test voltage under load, those are only with 5W resistors on 5V.

Any overheating components to touch on motherboard without overclock is not good sign, especially if they dont have big heatsink.

For instance my Z87-PRO just out of nowhere cutted out, nothing, no response, and after checking hot spots, after few seconds the south bridge would get insanley hot, meaning either south bridge has failed (Sorry not sure if North bridge and South are in one chip?) or capacitors/rest of small components.

 

[reg66]

oh bum! have already ordered it! never mind. yep, i think it's the southbridge that's gone, looks like i'll have to try and rma the board if i can (bought it as ex-display model with only a 3 month warranty, which has now passed). thanks for your help though

 

[Peter Martin]

so you can mark my remark about it being the motherboard correct