How To Read Your Power Supply Voltages | AnandTech Forums: Technology, Hardware, Software, and Deals
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How do I check if a CPU is getting power?
How can I check my PSU voltage? | Tom's Hardware Forum
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Unplug the power supply from any of the components inside the computer (or just remove it from the computer completely).
USE CAUTION HERE (Though you'd only be shocked with a max of 24 volts)
- Plug the power supply into the wall.
- Find the big 24-ish pin connector that connects to the motherboard.
- Connect the GREEN wire with the adjacent BLACK wire.
(If you're colorblind, the green wire sits between three black wires on one end and one more on the other) - The power supply's fan should start up. If it doesn't then it's dead.
- If the fan starts up, then it could be the motherboard that's dead. You can use a multimeter to check if there is power output from the power supply.
Most well-stocked geek-stores sell a "power-supply tester" that has all the appropiate connectors to plug each part of your PSU into, with spiffy LEDs indicating status of the various rails, connectors for IDE/SATA/floppy power cables, etc. They run ~$20 US.
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Unfortunately, there is no sure way of testing whether the fault lays with the CPU or motherboard without a good working reference pair to swap around the parts. As I stated previously, “It is unusual for the CPU to die” and so if you are going to swap items as a way of getting it working then guess at the motherboard .
I do not know what diagnostic steps you have taken to come to the conclusion that it is either the motherboard or CPU. If you have not done the following then do this before throwing money at random components.
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Strip PC down to parts and remove CPU from motherboard. Replace CPU, carefully checking for orientation, bent pins, contacts, etc.
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Check PSU for voltages on its own with DVM (Connect PS_On to ground to get it to power up.
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Power up motherboard outside of case. (It is not unknown for case mountings to short out motherboard circuits). So add heatsink of some kind to CPU (it is not going to be on for long). And you need just a smear of some grease between heatsink and CPU. Connect only PSU, keyboard and monitor. Short Power on connections on the motherboard briefly with screwdriver and it should power up. If working it should go into the BIOS and you switch it off. If that does not work then you are back to the dilemma of CPU or motherboard.
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If you are then sure that the fault lies with the motherboard or CPU does, then visually check the motherboard for any possible problems. If non seen, you could try a solder reflow.
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After all that you are back to guessing. Look for a very good friend using compatible parts which you can swap or try buying parts of e-bay.
Hello everyone! Me again!
My friend’s previously mentioned PC is still having issues. I’ve narrowed it down to the CPU. I want to rule out all other possibilities before telling him to replace the CPU.
I have a feeling it may be power, how do I test that I’m getting power through the 8 pin CPU power cable? I don’t have another PC here to test it on, but I do have a multimeter.
The PSU is a Corsair RM750x and the CPU is an i7 7700k in case this info is important.
The issue may also be cooling, but I have some idea on how to test that.
If anyone can let me know how to test power with the equipment I have at hand I would be very grateful.
Thank you
-Brandon