I'm building a new PC with a Ryzen 5 5600, MSI B550M PRO-VDH WIFI motherboard, ASUS RX 7600 8GB graphics card, MSI MAG A650BN 650W power supply, and 16GB of Kingston HyperX Fury DDR4 memory. The motherboard's CPU debug light remains on and there is no video output. I've removed and reseated the CPU, cleaned and reapplied the thermal paste, removed and reinstalled the CMOS battery, and tested different RAM sticks. The monitor is connected directly to the graphics card, and all parts are brand new. What else should I check, and is the CPU or motherboard likely to be defective?
2 Answers
First, verify that the 8-pin CPU power cable is connected to the motherboard and that the graphics card has its required power connection. Reseat the CPU, RAM, GPU, and all power cables, then try a minimal boot with one RAM stick in the recommended slot. Also make sure the display cable is connected to the RX 7600, since the Ryzen 5 5600 does not have integrated graphics.
The motherboard may need a newer BIOS version to support the Ryzen 5 5600, depending on when it was manufactured. Use the board’s BIOS Flashback feature to update it with a USB drive, following MSI’s instructions carefully. If the CPU debug light remains on afterward, inspect the CPU socket for bent pins and consider testing with another compatible CPU or motherboard to identify which part is faulty.

All of the parts are new, and the monitor is already connected to the graphics card. I’ll recheck the CPU power cable and try booting with only one memory stick.