Mobo or worse

[Simon]

Hi,
got a customer dell here (dimension 4700) I'm pretty sure it's the mobo
on the way out. Symptoms:
Powered on it will either work ok until it gets halfway through booting
then freezes. Diagnostic leds are all green.
Other times powered on no leds show at all, processor fan runs flat out
and thats about all.
I've tried another psu and memory and tried the onboard graphics rather
than the pci express card (was removed for that test)

Any other ideas welcome
thanks.

 

[philo]

Hi,
got a customer dell here (dimension 4700) I'm pretty sure it's the mobo
on the way out. Symptoms:
Powered on it will either work ok until it gets halfway through booting
then freezes. Diagnostic leds are all green.
Other times powered on no leds show at all, processor fan runs flat out
and thats about all.
I've tried another psu and memory and tried the onboard graphics rather
than the pci express card (was removed for that test)

Any other ideas welcome
thanks.

Try unplugging all but the video card.

Also... disconnect the HD

 

[Simon]

Try unplugging all but the video card.

Also... disconnect the HD

Thanks,
tried all that, still no go.
simon

 

[philo]

Thanks,
tried all that, still no go.
simon

Reset the bios

also...check the cmos battery


thought the machine should boot, even with no battery...
I've seen a few act flakey when the cmos battery was somewhere around 1.6
volts

 

[Simon]

Reset the bios

also...check the cmos battery


thought the machine should boot, even with no battery...
I've seen a few act flakey when the cmos battery was somewhere around 1.6
volts

Hi, thanks for the reply
nope, processor fan comes on flat out and nothing on the 4 diag leds on
the back of the pc.
I think I'll price up a replacement mobo and get back to the customer.

 

[Michael Cecil]

Hi,
got a customer dell here (dimension 4700) I'm pretty sure it's the mobo
on the way out. Symptoms:
Powered on it will either work ok until it gets halfway through booting
then freezes. Diagnostic leds are all green.
Other times powered on no leds show at all, processor fan runs flat out
and thats about all.
I've tried another psu and memory and tried the onboard graphics rather
than the pci express card (was removed for that test)

Any other ideas welcome
thanks.

Does it freeze up in the BIOS setup screen?

 

[Simon]

Does it freeze up in the BIOS setup screen?

Hi - yes it has on the few times it has worked

 

[Michael Cecil]

Hi - yes it has on the few times it has worked

Check that the CPU heatsink is correctly attached, not just that the fan is running.

 

[JAD]

Bench the board
clear the CMOS
no peripherals just PSU - video- memory- CPU/ HSF

 

[Simon]

Check that the CPU heatsink is correctly attached, not just that the fan is running.

yeah good thought, will try that and let you know thanks

 

[Simon]

Bench the board
clear the CMOS
no peripherals just PSU - video- memory- CPU/ HSF

OK latest.
reseated heatsink new compound etc. Cleared the bios and the system then
worked fine. I let it do a virus scan and this ran quite happily for an
hour or so until it froze again.
Symptoms are back to the original again!!
New mobo ? - it's almost going to be easier to recommend a new base unit.

 

[D Hunter]

Hi,
got a customer dell here (dimension 4700) I'm
pretty sure it's the mobo on the way out.
Symptoms: Powered on it will either work ok
until it gets halfway through booting then
freezes. Diagnostic leds are all green. Other
times powered on no leds show at all, processor
fan runs flat out and thats about all. I've
tried another psu and memory and tried the
onboard graphics rather than the pci express
card (was removed for that test)

Any other ideas welcome
thanks.

I have a few Optiplexs that did this. Turned out
it was the power supply.