I just finished building a new PC for my friend using parts he bought during Black Friday. After putting everything together and connecting all the peripherals, we powered it on, but it wouldn't post. The RGB lights lit up and the case fans started spinning, but the CPU and GPU coolers remained off, and the VGA troubleshooting LED on the Asus B650 TUF Gaming Plus motherboard was lit continuously.
We've tried various troubleshooting steps without any success, always facing the same issue: no post, and the CPU & GPU fans are static. Here's what we've done so far: we used a different CPU 8-pin cable, tested with just one CPU fan instead of both, and even tried only one DDR5 RAM stick instead of both. To make things even more confusing, I tested the GPU in my own PC, and it works perfectly! The CPU we have doesn't have integrated graphics, so that's not an option.
We want to identify the faulty component or any mistakes we may have made during the build. I'd like to avoid taking it to a repair shop as that's expensive. We're considering flashing the BIOS or checking for bent pins under the CPU cooler as our next steps. Here are the parts we used:
- Motherboard: Asus B650 TUF Gaming Plus
- CPU: AMD Ryzen 5 7500F
- CPU Cooler: Peerless Assassin 120
- GPU: RX 9060 XT 16GB
- RAM: 32GB Lexar DDR5 6000MT/s 38CL
- SSD: Samsung 990 Evo Plus
- PSU: Be Quiet! Pure Power 12 M
- PC Case: Montech 903 Air Max
Any insights or help would be greatly appreciated!
3 Answers
I’d really suspect the CPU cooler since it's not spinning at all. That’s a major red flag! The CPU cooler should always be running when the PC is powered on. It’s normal for GPUs not to spin their fans right away if they’re not under load. You should check if the cooler is connected properly; if the motherboard isn’t detecting it, it might not start up.
If the motherboard BIOS needs updating, it usually shows a red CPU LED instead of a white VGA light. Also, make sure your RAM sticks are in slots 2 and 4, counting from left to right from the CPU. They should be inserted with the label facing toward the CPU. When testing with a single stick, confirm that you’re using the right slot—as per the manual, sometimes it should be in slot 4.
The RAM is in A2 and B2 slots, and they’re inserted properly. I tested a single stick in A2 instead of B2, so I’m following that lead.
Did you connect the CPU cooler to the CPU header on the motherboard? Also, make sure that you've plugged in the main 4+4 CPU power connectors correctly. Sometimes people accidentally connect them to the optional header instead. Lastly, double check that the 24-pin connector is snugly in place. Trust me, it’s easy to overlook these connections! If you’re using an AIO, don’t forget to connect the SATA power and USB port for the waterblock too.
I used the splitter that came with the PA120 for the fans and connected it to the CPU fan PWM socket. I also checked the optional PWM socket, and we still had the same problem. I made sure the 8-pin power cable is in place, but we didn’t use the second 4-pin since it’s not necessary for this CPU.
If the CPU itself is faulty, would the coolers still spin? If they wouldn’t, then I agree it’s likely the air cooler; otherwise, I might lean more toward the CPU being the issue.