Member Avatar for compcrash

I built this computer 5-6 years ago. It has only frozen maybe 2 times and crashed maybe 3. What I mean when I say wont start is, It turns on motherboard lights come on, all fans work, everything seems to be going normally but it stays in high run mode (when it is louder at the start of turning the computer on) and the keyboard lights don't flick on and off and the monitor has no reaction, the mouse lights up, there are no beeping sounds, the pcu warms when computer is on, I have moved all the ram to different slots, I have moved the video card to different slots, I took the whole computer apart and back together, all the wires are plugged in, I think the hdd is spinning (its extremely quiet), and I cant think of anything else to do. Any suggestions? Please help. Sorry for the terrible run on sentences and bad grammar possibly, I just want my computer working again.

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  • Latest Post Latest Post by caperjack

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This thread is a textbook example of a PC that "powers on" but never posts. Thanks to 's nudge to isolate memory and to for following through, the root cause was a single bad DIMM. Below is a concise, safe diagnostic routine and a few checks to make this failure faster to diagnose on other older rigs.

  • Safety first: always disconnect mains before changing parts. Do not run a CPU without its heatsink and fan except for an instant bench-check; prolonged runs without a cooler can cause permanent damage.
  • Breadboard the system: unplug all storage and extra cards, fit only CPU + cooler + one RAM stick + GPU (only if no integrated video) + PSU + monitor + keyboard + speaker. Use the board's recommended primary DIMM slot (check the manual).
  • Clear CMOS (battery removal or jumper) before re-testing to eliminate BIOS misconfig. Fit one stick of RAM at a time and try every stick in the same slot; intermittent faults often show only with particular sticks or slots.
  • Add a POST speaker or read motherboard POST/debug LEDs — these give immediate clues that fans and LEDs alone cannot.

For memory verification: boot a Memtest86 USB and run multiple passes (several hours if possible). Windows Memory Diagnostic is okay for a quick check but less thorough. Any reproducible errors in Memtest mean replace that module (or swap it into another machine to confirm). When replacing, match speed/voltage/timings or use a matched kit.

Other things to inspect: visually check the motherboard for bulging or leaking capacitors, burned traces, bent CPU socket pins, and loose power connectors. If a system still shows no POST with minimal parts, test the PSU voltages with a multimeter or PSU tester or try a known-good PSU. On older systems, RAM and caps are common culprits — keep a spare, run periodic memory tests, and avoid diagnostic shortcuts that risk hardware damage.

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Member Avatar for caperjack

the pcu warms when computer is on


assuming you mean "cpu" its not wise to let a non-booting computer run till the processor gets hot .you may be just doing more harm ,it may already be too late ,no way of telling that i know of ,except changing the CPU

Member Avatar for compcrash

I only had it on for 5 seconds without the heatsink/fan to check that the cpu was working.

Member Avatar for caperjack

it only takes 5 seconds if it a AMD cpu ,good luck

Member Avatar for compcrash

it only takes 5 seconds if it a AMD cpu ,good luck

It is intel, I have another older processor Im going to try. So you think it is the processor and not anything else?

Member Avatar for compcrash

I tryed a different processor, Same result.

Member Avatar for caperjack

It is intel, I have another older processor Im going to try. So you think it is the processor and not anything else?

no,not positive ,5or6 yr old computer it could be anything ,try it with just one stick of ram at a time

Member Avatar for compcrash

no,not positive ,5or6 yr old computer it could be anything ,try it with just one stick of ram at a time

Thank you so much, 1 of my sticks of ram is faulty. Have a good day sir, You are my hero!

Member Avatar for caperjack

your welcome, glad it worked for you

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