u/salvatore384

My Dell OptiPlex 3040 MT, (I5-6500 16gb ram) randomly started freezing/crashing recently. At first the CPU fan would get really loud and the whole PC would freeze completely with no blue screen. I changed the thermal paste and it worked for a few days, but now it won’t turn on at all.

Current symptoms:

• Fans spin and power comes on
• No display / no signal
• No Dell logo or BIOS screen
• Mouse LEDs don’t turn on anymore
• Keyboard lights sometimes work
• No beep codes
• After sitting on for a while, the PC sometimes shuts itself back off (Due to no display).

Things I already tried:

• Different HDMI/display
• Reseating RAM
• Trying one RAM stick at a time
• Checking cables/connections

I’m trying to figure out if this sounds more like:

• bad PSU
• dead motherboard
• CPU issue
• RAM issue or something else.

Any help appreciated because I’m stuck and don’t really know what part failed, And Im just trying to see if its even worth trying to fix.