Member Avatar for anguz

Hi,

I'm new here, so hello and thanks in advance for your help.

I've had an HP Pavilion 511k for years and it hasn't given me any trouble, but over a year ago I had to go to another country and left it with a friend. Now that I'm back, he returned it but it doesn't work. He tells me he almost didn't use it, but one day he tried to turn it on and it just didn't.

Here are the specs:

I don't get anything on the screen or beeps from the computer.

There is something peculiar, when I plug the cable to the power supply, the motherboard's green led turns on (dunno what it means) and the CPU's fan starts spinning, even though I didn't push the power button on the front. Actually, when I push the button, nothing happens.

I disconnected and connected back everything (HDD, floppy, DVD burner, RAM sticks, battery) and tried booting after each change: nothing.

Please help.

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Dani AI

Generated

Quick expert summary and a focused troubleshooting sequence to try before replacing the motherboard/CPU.

The CPU fan spinning and the green LED lighting as soon as the PSU is plugged in generally means the standby rail is present (ATX 5VSB) — that can power LEDs and some fans even with the front power switch untouched. That behavior narrows the likely causes to: a shorted/stuck front-panel power switch or cable, a motherboard fault (failed power-control circuitry or bad caps), or a PSU rail that won’t come up under the motherboard’s control. was right to check power connections and PSUs; here are the practical next steps and what each test isolates.

  1. Isolate the front panel
  • Remove the case’s power-button cable from the motherboard. If the board behaves differently (fan/LED stop or the button response changes) the case/switch or wiring is at fault.
  • If no front-panel cable is available, try momentarily shorting the two power-switch pins on the mobo with a screwdriver to attempt a manual start (only when powered and done briefly).
  1. Minimal bench-boot
  • With PSU unplugged, remove all nonessential devices (drives, cards, extra RAM). Leave CPU, one RAM stick in the recommended slot, and video.
  • Attach a small internal speaker to the speaker header (many OEMs omit this). Plug in and try to start — listen for POST beeps. No beeps + speaker absent can hide useful diagnostics.
  1. CMOS and visual checks
  • Clear CMOS (jumper or remove battery ~10–15 minutes). Inspect the motherboard closely for bulging/leaking capacitors, scorch marks, or cracked components (common on older boards). Visual cap failure is an inexpensive, common repair (recap) compared with a new board.
  1. Power-rail verification and next steps
  • If available, measure PSU rails (+12V, +5V, +3.3V) under load or try a known-good PSU again on the bench. Try the board outside the case on nonconductive surface to rule out standoffs/shorts.
  • If all tests fail, a POST card or shop bench test will confirm whether the board’s power regulation or southbridge/BIOS is dead. Given age, replacing the board may be reasonable — but check case form factor and front-panel/header differences first (HP OEMs sometimes use proprietary connectors).

Safety: always unplug power before probing, ground yourself, and avoid powered metal contact.

Member Avatar for mechbas

The fan moving on your PSU sometimes gives a false positive.
Before you take that drastic an action: unplug the psu from the wall, disconnect then reconnect all power connectors to the system board.

Member Avatar for anguz

Okay, I did that, but still nothing. :(

Member Avatar for mechbas

If you've another PSU available that you know is working, try that.

Member Avatar for anguz

I had not thought about doing that. I just tried it, but the result was the same... I used a friend's bit older HP Pavilion.

It also has a socket 370 processor, so I tried switching CPUs, but my computer still behaves the same with his processor, and I know his works.

I'm starting to consider buying a new mobo and CPU. :(

Member Avatar for mechbas

Seems that you've just about exausted the other possibilities which leaves you little other choice. If it was going to fly it already would have.
If cost is a issue you might try the mobo first, whatever the CPU speed, etc. it's going to be the most expensive piece of hardware.

Member Avatar for anguz

Well, yeah, but it's being pretty hard to find socket 370 parts that aren't used in Mexico, at least it's being for me, and for not much more money I found a VIA mobo with processor, which seems a better way to go. I'd only need to add a new RAM to that, since it uses DDR2 instead of the DDRs I have. :icon_rolleyes:

So, in the end, instead of a used mobo (without USB2) and CPU ~1Ghz at around $50, I could get a new kit at ~2.5Ghz (with USB2, which is important for me) for $70 (+ DDR2 RAM, another $35 or so... :icon_frown: ). I only have to research the model and see if it's good, I have never heard of the VIA brand before.

I'm also not sure if that mobo's form factor is uATX, but I think I can make it fit in the case anyway, or make a new one if needed.

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