I've been doing a fair bit of googling, asking friends and reading old posts in this forum. If you'd be so kind I could use a little help :)
Newly upgraded self-assembled Desktop won't POST and simply loops in a 5 second cycle of cutting power then trying to re-start.
- Connect mains power and turn on the PSU switch
- Pushed the front power switch
- Power LED comes on
- PSU fan starts
- HDD light flashes once.
- After about 5 seconds the CPU fans starts
- After a further half second the system powers off by itself
- At the same time the HDD LED flashes once and the power LED goes out.
- No motherboard beeps.
- After 5 seconds it repeats steps 3 to 8 by itself
- This cycle will continue until I turn cut the power.
- When I do that it attempts to continue the cycle 5 seconds after it shut itself down last time. However it only manages to get the PSU fan running before turning off about half a second later. (as if it had a residual charge)
Re-built old PC with these new components (checked for compatability before purchase.)
The PC was running smoothly for nearly two weeks!!!
- Q6600 (not O’C)
- 4Gb Corsair 800MHz (4x1024) 4-4-4-12
- Sapphire 8800gts 320mb PCI-e with latest drivers
- Gigabyte GA-P35C-DS3R bios F4g (flashed with latest) All mobo drivers installed from Manf CD.
- Coolmaster eXtreme Power 650W
- Thermaltake HSF and Artic silver gunk.
- Vista Home Premium 64 bit (new install on reformatted HDD) fully updated
- CCFL tube just for fun
Used these existing parts:
- X-Fi XtremeMusic sound card (6 mth old) with latest Vista drivers
- 3x Seagate HDDs SATA & SATA II (various ages)
- LG Burner (Six mth old), needed firmware update but worked fine.
- No floppy installed
Last action before problem: Un-installed Adobe Acrobat 8.0, restarted. Machine POSTed. Windows attempted to start but hung at progress bar. Hit re-set switch. Restart cycle commenced.
Actions taken so far:
- Removed these devices one at a time (tested after each, not in this order)
- RAM (one at a time and all together in and all together out; tried each stick in different slots on it's own (took a long time))
- Video Card
- Sound Card
- DVD Burner (no floppy installed)
- PCI slot SATA expansion thingy
- PCI slot USB expansion thingy
- Case fans
- CCFL tubes
- Swapped out the CPU fan
- Did all this until only these items remained plugged into the Mobo:
- the CPU fan,
- the 20 pin main power
- the 4 pin main power that sits next to the 20 pin, (Also tested without it)
- the 4 pin ATX 12V power
- Front panel power & reset switches and Power & HDD LEDs
- and the ram
- Double checked all leads, plugs etc
- Removed the battery for 3 minutes and used the reset jumper.
- Removed front case bezel to ensure switches & LEDs weren't shorting & inspected the entire case for possible shorts.
- Re-seated the whole motherboard to make sure it wasn't touching the case.
- Swapped out the PSU
- Removed the Motherboard completely outside the case and tested to elimate shorts
So, I am left with three possibilities.
The CPU is dead.
The Motherboard is dead.
Neither the CPU or Motherboard.
How, kind readers, do I tell which? I don't have access to another Motherboard or CPU :(