No Power to MoBo, Replaced PS w/650W still NO POWER, help.

hbi1000

Hi,

Problem: Machine will not power up, merely spins cpu cooling fan and begins to power up disks before loosing all power after 1-2 seconds. Then pushing power button does nothing, no fans or disks spinning.

Machine:
MoBo: PC400 M930 478
Processor: P4 1.2GHz (non-hyperthreading)
1 GB PC133 SDRAM memory (2 -512s)
10 MB ethernet on mobo
2 serial connections
1 parallel port
2 USB 1.0 ports
Sound on mobo not used.
PS: Brand new MGE 600 Watt PS (fully tested by me)
Disk Drives: 3 WD 80 GB drives
Optical Drives: 1 - CDROM R/W, 1 - DVD R/W
AMR: 1 - modem
AGP: 4x - nVidia p162 video card w/ onboard cooling fan

PCI:
Sound Blaster Live CT4830
1 IDE adapter board w/ 2 controllers
1 5 bay USB 2.0 adapter
1 2 bay Firewire/3 bay USB 2.0 adapter

Other:
3 cooling fans (1 over heatsink, 1 front intake, 1 rear exhaust)

Current Observations (with only monitor and PS/2's connected):

1. PS rechecked and OK w/PS checking device,
2. This is a real mystery to me: With mobo atx 20 pin main power disconnected and power button pushed all fans, disk drives, spin up to what seems to be operating speeds (I shut it down after 5 seconds). However, once atx 20 power re-connected the original problem of a 1-2 second "spurt" of power to fans and disks occurs.

Unusual Traits: When friend brought me the machine it acted in a similar fashion with 450W PS. I thought it was underpowered with all of the PCI connections, and to test my theory I removed power from the two PCI connected disk drives and hit the power button and the machine began to POST. Now that I've replaced the PS it won't even do that?

I'd appreciate any suggestions or thoughts as to this situation, as I've already spent $79.00 on a good PS and it doesn't fix the problem :banghead: .

Thanks,
HBI1000

muddocktor

I've seen symptoms like you describe with a bad or improperly connected floppy drive(on the power cable) before. Have you tried stripping down to where you just have the hsf and vid card hooked up and installed and see if you can get it to boot to bios? Also, another thing crossed my mind too, but I don't know if an old P4 system has support for this feature. I know on most socket A AMD mobos that they have a setting in bios that shuts down the machine if it doesn't have a fan that has an rpm sensor hooked to the cpu fan header. Does that old P4 mobo have that feature in bios?

Leonardo

Does that old P4 mobo have that feature in bios?

I think all socket 478 boards have CPU fan detection setting option.

hbi1000

muddocktor wrote:

I've seen symptoms like you describe with a bad or improperly connected floppy drive(on the power cable) before. Have you tried stripping down to where you just have the hsf and vid card hooked up and installed and see if you can get it to boot to bios? Also, another thing crossed my mind too, but I don't know if an old P4 system has support for this feature. I know on most socket A AMD mobos that they have a setting in bios that shuts down the machine if it doesn't have a fan that has an rpm sensor hooked to the cpu fan header. Does that old P4 mobo have that feature in bios?

hbi1000

Thanks for the advice. I disconnected then reconnected the floppy's power cable, and hit the power switch and the entire system booted right into XP. I should have remembered that as I run into it rebuilding old PC's for a local charity. Too close to home I guess. I'll let the system run for several hours, then try multiple reboots to see how "well" it runs with its "new PS." Thanks for the advice -- it worked.

HBI1000

muddocktor

Glad to hear that it was something as simple as the floppy drive, hbi1000. I know that floppy drives being connected wrong have thrown me for a loop in the past myself, giving the exact symptoms you described. Now all you need to figure out is if the floppy drive is bad or you had the power connector hooked up wrong (I've done that too when plugging power into it in small cases).

And Leo, since that system has a P4 1.2 proc, it is a socket 423 Williamette board, which I don't have much experience messing with. So I don't know if it has the auto shutdown with no fan connected feature, since it's such an old board.