I'm having an issue with my Dell Dimension 5100 desktop. After running for several minutes, the monitor shuts itself down. (The monitor power light turns solid yellow.) Just prior to this happening, the computer will sound like it is running hard and loud. However, the computer does not shut down, just the monitor. The only way to get the monitor back is to power off the system and reboot. After rebooting, everything appears to work just fine...for a while. Then the monitor goes away again. I replaced the monitor cable/power cord but problem continues. No error messages, no blinking lights. power light on computer reminas green.
(FYI-The fan was replaced on the computer about a year and a half ago. At that time, the entire system would shut down.)
I would appreciate any suggestions! Thanks!

I guess your gpu get's too hot, to continue working properly.

Check if the gpu fan is running properly, and if the gpu heatsink is clean and dust free. You don't want any dust and dirt to block the airflow on the gpu heatsink. :)

You can also download the free GPU-Z utility, and check the gpu temp. on the "sensors tab"