I'm troubleshooting an AM4 system that powers on but never produces a display signal. The original build used a Ryzen 5 5500, ASUS PRIME B550M-A WIFI II, 16 GB of DDR4-3200 memory from a working PC, an RTX 4060 Ti from another working PC, a Patriot P320 256 GB SSD, and an MSI 650 W power supply. All fans spin, but there is no image over DisplayPort or HDMI, even after trying multiple known-good cables, monitors, and inputs.
I tested one RAM stick at a time, tried additional memory, swapped the power supply, and replaced the motherboard with two Gigabyte B550M Gaming X WiFi boards. I also cleared CMOS and used Q-Flash Plus to install compatible BIOS versions. Removing the RAM and graphics card produced no beep codes, even after trying two internal motherboard speakers. Finally, I replaced the CPU with a Ryzen 5 5500F and tested with a known-working RTX 4070 Super, but the behavior remained unchanged.
The display cable is connected to the graphics card. I'm beginning to suspect that I'm overlooking something basic, such as a monitor/input issue, a power or front-panel connection, a POST state, or an incompatibility. What else should I check?
3 Answers
Try a true minimum configuration outside the case: motherboard, CPU and cooler, one memory stick in the recommended slot, graphics card, and the 24-pin and CPU EPS power connectors. Disconnect the SSD, front USB/audio headers, extra fans, and case switches, then start it by briefly shorting the power-switch pins. Carefully recheck that the CPU power connector is the EPS cable rather than a PCIe cable, and inspect the socket and CPU for bent or damaged contacts. A misplaced front-panel or USB connector can prevent startup.
The lack of beep codes may not prove much. Many boards need the speaker connected to the exact speaker pins and may not beep for every failure, while some speaker kits are faulty or have the wrong connector. Also, RAM working in another PC does not guarantee that it is stable or compatible here, so test one module at a time in the board’s recommended slot and run a memory test if the system can boot. Confirm the exact BIOS support for the installed CPU and verify that the flash process actually completed rather than only copying a file to the USB drive.
First determine whether the machine is actually reaching POST. After powering it on, press Num Lock or Caps Lock several times and see whether the keyboard LED changes. If it does, the system may be booting normally and the problem is probably the monitor input, cable, resolution, or graphics output rather than the CPU or motherboard. Use one known-good monitor and cable, manually select its input, and connect directly to the graphics card. The 5500 and 5500F do not have integrated graphics, so the motherboard video ports cannot provide an image.
Since the same display setup has worked with the primary computer, I’d focus on whether this machine is completing POST and whether the keyboard responds. That separates a video-output problem from a system that is not booting at all.