but when you test the power supply with an older motherboard it
powers up the pc ok and outputs picture to monitor screen
The newer more power hungry mobo works ok though with another power
supply and before it also worked fine with now problematic PS
Replaced output filtering capacitors inside the power supply although
visually they looked ok but still the same problem, any ideas what to
check next please?

On 1 sep, 14:01, poster wrote:
but when you test the power supply *with an older motherboard it
powers up the pc ok and outputs picture to monitor screen
The newer more power hungry mobo works ok though with another power
supply and before it also worked fine with now problematic PS
Replaced output filtering capacitors inside the power supply although
visually they looked ok but still the same problem, any ideas what to
check next please?

There is nothing else to check. You just determined what is wrong: the
original PSU. The fact that the PSU can power an older motherboard,
just proves that the PSU is not powerful enough to power your new
motherboard. ATX PSUs tend to degrade over time... capacitors lose
capacitance, ripple increases... I know that you replaced the
capacitors, but with what? Did you used low esr replacements? What is
the wattage of the PSU? What CPU and motherboard are you using?

"poster" wrote in message
...
but when you test the power supply with an older motherboard it
powers up the pc ok and outputs picture to monitor screen
The newer more power hungry mobo works ok though with another power
supply and before it also worked fine with now problematic PS
Replaced output filtering capacitors inside the power supply although
visually they looked ok but still the same problem, any ideas what to
check next please?

Did I mention that an upgraded power supply can be better than repairing a
marginal power supply because:

The time it takes to troubleshoot the marginal power supply to component
level may mean that you get to keep the old junk because the customer went
out and bought a new computer. Any time and money you invest is
unrecoverable.

It is more worthwhile to quickly replace the bad power supply or build a
whole new machine with new (often sale priced) parts for those who would
more appreciate that.

If this is your own machine and you are flat broke/unemployed with time on
your hands, you have my sympathy and prayers.

Have you checked the output voltages before and during failure? Most
supplies have shut down protection from out of tolerance voltage or current.
Even a noisy adjustment pot can trip a supply.