Member Avatar for rafleet

Hi, first time poster, but long time techie.

I have an HP 864N desktop system that has been my workhorse since I purchased refurbished from TigerDirect 4 years ago. I use it for literally everything - web design, coding, CD and DVD mastering, video and audio editing, etc.

Unfortunately...it's deader than a Monty Python parrot.

Here's what I've done to troubleshoot the issue.

A. The problem first developed months ago with an alert that the CPU fan was non-functional. Purchase a replacement CPU fan...boot up...get same error. Having just taken my A+ cert last year, figured it was the power supply (not the first time I've had a PS issue, but a first for this box).

B. Replace the 200 watt OEM PS with a 400 watt non-OEM PS...this gets the box going again for next several months. Box is now out of warranty from TD, as well as past the 2yr extended warranty I purchased

C. Start having issues with the system not wanting to power on when the on/off button is pressed.

D. Pop the box open, remove the front fascia, check all wire connections, reseating, and checking each leg of the two power button wires for continuity from button to motherboard.

E. Picked up an Antec ATX power supply checker () and the new power supply tests out fine, as well as two PS I've taken out of older boxes (but which won't fit the 864N case) so I'm comfortable in saying the new PS is working fine.

F. Replace the tiny momentary-on switch with a couple of different MO switches, to no avail. Box still dead.

G. Last part of the puzzle before going to MB, I replace the AC cord adapter, Trying several different cables of all ages. Dig into my parts stash, and find a never used AC cable. Plug it on. Try one last time...IT BOOTS!.

H. Box stays on for a few weeks, letting me get a lot of work done. Only power down a couple times, and hot reboot a couple of times a day (sadly).

I. Finally, last power off after a long day of use. Next morning completely dead again. No boot. Try AC cables, switch check, continuity check for red/black wires from switch to motherboard...still good. PS checked again...still passes.

J. Lastly, another google of dead machines, brings me here to this forum. I now think the motherboard is the problem. I know it can be replaced, and that's fine, and cheaper than a new box...for now.

So, have I missed anything? Any concurrance on the MB being the issue?

Any ideas or suggestions appreciated.

Rich

  • 2 Contributors
  • 1 Reply
  • 214 Views
  • 21 Hours Discussion Span
  • Latest Post Latest Post by caperjack

Dani AI

Generated

Brief expert note building on ’s troubleshooting and ’s suggestion that the motherboard is failing. The pattern described is consistent with a marginal or failed board, but a few focused checks will separate a truly dead motherboard from a marginal power/connector problem and avoid an unnecessary purchase.

High‑yield electrical checks (safe, low‑effort):

  • Verify the standby rail (5VSB) with a DMM while the PSU is plugged in and switched on; it should be ≈ +5 V.
  • Observe the PSU start signal (PS_ON): the motherboard must pull PS_ON low to start the supply. If 5VSB is present but PS_ON is never pulled low, the fault sits on the board.
  • With the PSU running, confirm the main rails (+3.3, +5, +12 V) under the minimal load of CPU+one RAM stick. These measurements are the quickest way to separate PSU vs. motherboard problems.
    Safety note: mains work and probing power rails carry shock risk; power should be removed before reconnecting headers and ESD precautions used. Seek assistance if unfamiliar with live measurements.

Visual and mechanical checks that often catch intermittent failures:

  • Inspect motherboard electrolytic capacitors for domed tops or electrolyte residue and check for burn marks or cracked solder near the ATX connector and VRM area.
  • Bench the board outside the case on a nonconductive surface with minimal components to rule out a short to the chassis or a bad front‑panel harness.
  • Check the CMOS battery voltage and look for loose standoffs or misplaced screws that could short traces.

If the board is confirmed dead, options include replacing with an exact compatible board, repairing obvious capacitor/VRM damage if comfortable with soldering, or salvaging CPU/RAM/drives and sourcing a used OEM board from reputable sellers. Reuse of a known‑good ATX PSU is recommended. Professional repair is sensible when live measurements or board‑level troubleshooting are unfamiliar.

Member Avatar for caperjack

as you say ,a dying mother board that finally died ! sounds like it to me

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.