I replaced my motherboard and power supply, and the motherboard worked normally in the BIOS before I installed the new PSU. With the new Cluster 850W fully modular unit, the PC powers on but produces no video and the motherboard's VGA debug LED remains lit. I already reset the BIOS, tried different display cables, and tested the new PSU in my brother's computer, where it powered on normally. However, when I reconnect my old Aigo Warrior AK 500W, my own PC works as expected. My system has a Ryzen 5 4500, MSI Pro VDH WiFi motherboard, 1TB XrayDisk SSD, 2x8GB HyperX RAM, and an RX 5500 XT graphics card. What could cause the VGA light to appear only with the new power supply?
1 Answer
Start by checking the graphics card power connection with the new PSU. Make sure you are using the PCIe/VGA cable supplied with that exact power supply—not a CPU/EPS cable and not a modular cable from the old PSU. Modular cables are not universally wired the same way, and mixing them can prevent the GPU from starting or damage components. Reseat the card and its power connector as well. A PSU working in another computer does not prove that its PCIe output, cable, or protection behavior is correct for this particular system.
A normal motherboard-to-PSU incompatibility is very unlikely here. The motherboard mainly needs standard ATX and CPU power, while the VGA LED points more toward the GPU, its PCIe cable, or a power-delivery problem. Compare the exact PCIe cable and connector behavior with the old PSU, and avoid using any modular cable that did not come with the new unit.
All of the connections appear to be correct, and the PSU was tested by a technician in another computer. Could this instead be an incompatibility between the motherboard and the power supply?