I built my PC about five years ago, and everything was running smoothly until suddenly, last Friday, it just powered off. I noticed a faint smell and figured it was the power supply (an EVGA Supernova), so I took it out and did the paper clip test—nothing. I ended up buying a new Corsair RM750e PSU and installed it, but I'm still experiencing no power at all: no fans, no lights, nothing.
I've checked everything: I did the paper clip test on the new PSU, and it works fine. I swapped power cords and tried different outlets, all of which function properly. I removed my GPU (an MSI GeForce RTX 3060) and still got nothing. I also tried four different RAM sticks, swapping them one at a time in the primary slot, and none of that helped. I replaced the motherboard cable with the one from Corsair, but no change. I pulled the CMOS battery; it's showing over 3 volts, but still no power whether it's installed or not. I even tried jumping the power switch connector on the motherboard, but that didn't work either.
At this point, I'm really stumped. The new PSU is wired correctly, with the motherboard, SATA, and CPU cables all plugged in. A friend who has 30 years of IT experience recommended reseating the CPU, but wouldn't the motherboard show signs of power even if the CPU were dead? The board has debug LEDs for CPU, DRAM, VGA, and BOOT, which should light up if it's getting power.
If I were to take this to a shop, would it be better to assemble everything back together, and should I use the old PSU or the new one? Any advice would be greatly appreciated!
3 Answers
Given the cable issue, there's a good chance your motherboard is toast. I suggest you try powering it up with just the 24-pin cable connected—remove all RAM, the GPU, and even the CPU cable if you can. If the board is working, it should show some signs of life!
Wait, you said you replaced the motherboard cable with a new one from Corsair, right? But are you still using the old EVGA cables with it? That could fry everything! **Don’t ever mix power supply cables!** They have different pinouts, and using the wrong cables can definitely damage your components. If that's the case, remove those old cables immediately and hope you didn't ruin your motherboard!
I learned something new from this! Thanks for the heads up.
Yeah, modular power supply cables aren’t interchangeable—you could potentially fry your components if you used EVGA cables on a Corsair supply even if they seem to fit. Each brand has its own wiring for the pins, and even months-old cables from the same brand might not work for different models. Definitely double-check that!
Wow, that's a huge oversight. I learned my lesson about modular supplies today.
I'll try that method. Thanks for the suggestion!