My PC powers on, gives one normal-sounding beep, shuts off, and then starts again. The fans and system seem to turn on, but I get no display. The hardware is an Intel Core i5-9500F, a GeForce GTX 1050 Ti, two 8 GB RAM sticks, and a Gigabyte B365M H motherboard. Since it beeps once, I'm wondering whether that means it passed POST and what else could be causing the lack of video output or the restart.
2 Answers
One beep often indicates that POST completed successfully, but beep codes depend on the motherboard and whether a case speaker is actually connected. Check whether you can enter the BIOS, whether the display shows a motherboard logo, and whether the computer remains on after restarting. Also try another display cable or monitor and make sure the graphics card is fully seated in its PCIe slot. Since the i5-9500F has no integrated graphics, the monitor must be connected to the GTX 1050 Ti.
A brief shutdown followed by a restart can have several causes, including a weak power supply, a memory or GPU connection problem, or a CMOS setting issue. Reseat both RAM sticks as well as the graphics card, then try starting with one RAM stick at a time. You can also clear the CMOS: unplug the PC, remove the CMOS battery, hold the power button several times, wait a few minutes, reinstall the battery, and try booting again. The CPU is using a standard fan cooler, and the GPU has already been reseated, so checking the RAM and PSU would be useful next.
The CPU is cooled by a regular fan, not an AIO pump. I’ve already reseated the graphics card, but I’ll check the RAM and try clearing the CMOS.