Whining PSU

[scotoma]

Hi all

My main question is, what makes the capacitors on a PSU whine?

The whining PSU is a new Mercury 300W powering a Gigabyte KT400 mobo, 40GB
Samsung ATA100, AthlonXP 3000 "in a box" with supplied fan, 512MB DDR333,
nVidia Riva TNT2 M64 (lol), 1x case fan, 52x CDRom, onboard sound, usb2 x 4.
OS is windows XP Pro.

I've tried changing the new 300W PSU with an old and known to be quiet same
brand Mercury 300W PSU which used to silently power a Chaintech Apogee mobo,
AthlonXP 1800, dual fan, 512MB DDR266, nVidia FX5200 128MB, 1x case fan,
200GB Maxtor ATA133, Pioneer 107, Plextor 48a, Yamaha SW1000XG sound card,
SBLive 5.1 sound card and 6x usb. OS is Windows XP Home.
Note that I've since put a 400W PSU in the AthlonXP 1800 system, it's still
quiet.
Surely the AthlonXP 1800 system (300W PSU) was drawing more power than the
AthlonXP 3000 system yet the PSU's are squeeling like **** on the AthlonXP
3000 system????

Any help (before things go bang! lol) would be great

Scotoma

 

[Patrick]

Hi all

My main question is, what makes the capacitors on a PSU whine?

The whining PSU is a new Mercury 300W powering a Gigabyte KT400 mobo, 40GB
Samsung ATA100, AthlonXP 3000 "in a box" with supplied fan, 512MB DDR333,
nVidia Riva TNT2 M64 (lol), 1x case fan, 52x CDRom, onboard sound, usb2 x 4.
OS is windows XP Pro.

I've tried changing the new 300W PSU with an old and known to be quiet same
brand Mercury 300W PSU which used to silently power a Chaintech Apogee mobo,
AthlonXP 1800, dual fan, 512MB DDR266, nVidia FX5200 128MB, 1x case fan,
200GB Maxtor ATA133, Pioneer 107, Plextor 48a, Yamaha SW1000XG sound card,
SBLive 5.1 sound card and 6x usb. OS is Windows XP Home.
Note that I've since put a 400W PSU in the AthlonXP 1800 system, it's still
quiet.
Surely the AthlonXP 1800 system (300W PSU) was drawing more power than the
AthlonXP 3000 system yet the PSU's are squeeling like **** on the AthlonXP
3000 system????

Any help (before things go bang! lol) would be great

Scotoma

1. counterfeit capacitors were shipped to all of the PSU
manufacturers... and the capacitors were weak, defective...
still tracking down all the products, in which those bad caps were used!
Includes Mainboards, PSUs...

2. PSUs are all overrated, by 10% minimum, up to 40%, for the cheapo
ones. And, any load on the PSU changes from the start-up spike, to each
device use like CDrom burning, hard drive spin-up...

I immedidately disconnect any noisy PSU, and get a replacement.

 

[Johannes H Andersen]

Hi all

My main question is, what makes the capacitors on a PSU whine?

The whining PSU is a new Mercury 300W powering a Gigabyte KT400 mobo, 40GB
Samsung ATA100, AthlonXP 3000 "in a box" with supplied fan, 512MB DDR333,
nVidia Riva TNT2 M64 (lol), 1x case fan, 52x CDRom, onboard sound, usb2 x 4.
OS is windows XP Pro.

I've tried changing the new 300W PSU with an old and known to be quiet same
brand Mercury 300W PSU which used to silently power a Chaintech Apogee mobo,
AthlonXP 1800, dual fan, 512MB DDR266, nVidia FX5200 128MB, 1x case fan,
200GB Maxtor ATA133, Pioneer 107, Plextor 48a, Yamaha SW1000XG sound card,
SBLive 5.1 sound card and 6x usb. OS is Windows XP Home.
Note that I've since put a 400W PSU in the AthlonXP 1800 system, it's still
quiet.
Surely the AthlonXP 1800 system (300W PSU) was drawing more power than the
AthlonXP 3000 system yet the PSU's are squeeling like **** on the AthlonXP
3000 system????

Any help (before things go bang! lol) would be great

Scotoma

Any whining sounds are more likely to come from transformer coils with
some loose windings. The PSU switching frequency is much higher than the
net frequency, this reduces the size and weight of the coils. Are you sure
it is the capacitors? I can't see how this could work. In any case it
sounds like the PSU is stressed out.

 

[ric]

My main question is, what makes the capacitors on a PSU whine?

What makes you think that it is the capacitors that are whining?
Usually, it is the magnetics that whine in SMPS.

 

[William W. Plummer]

My main question is, what makes the capacitors on a PSU whine?

I find it easier to believe the fan bearings are the source of the whine.

 

[scotoma]

1. counterfeit capacitors were shipped to all of the PSU
manufacturers... and the capacitors were weak, defective...
still tracking down all the products, in which those bad caps were used!
Includes Mainboards, PSUs...

2. PSUs are all overrated, by 10% minimum, up to 40%, for the cheapo
ones. And, any load on the PSU changes from the start-up spike, to each
device use like CDrom burning, hard drive spin-up...

I immedidately disconnect any noisy PSU, and get a replacement.

Hi Patrick

Thanks for your reply
I'll get a new 400W PSU.

Scotma

 

[scotoma]

Any whining sounds are more likely to come from transformer coils with
some loose windings. The PSU switching frequency is much higher than the
net frequency, this reduces the size and weight of the coils. Are you sure
it is the capacitors? I can't see how this could work. In any case it
sounds like the PSU is stressed out.

Hi Johannes H Andersen

Thanks for your reply
It was just a very uneducated guess that it was the capicitors.
I will try a higher rated PSU.

Scotoma

 

[scotoma]

What makes you think that it is the capacitors that are whining?
Usually, it is the magnetics that whine in SMPS.

Hi ric

Thanks for your reply

It was an uneducated guess that it was the capacitors.

Scotoma

 

[Stuffed]

1. counterfeit capacitors were shipped to all of the PSU
manufacturers... and the capacitors were weak, defective...
still tracking down all the products, in which those bad caps were used!
Includes Mainboards, PSUs...

My board that I posted about a while ago came back fixed

It turns out not only were 3 caps failing, one in a big way, but one of them
was also fitted the wrong way round when the board was made! Which might go
some way to explaining the failure, and the fact the board always made some
interference type noises.

It'll have cost me about a tenner to get it fixed though, so no point
chasing anyone up over it. Just surprised a Chaintech board was put together
like that.

 

[scotoma]

I find it easier to believe the fan bearings are the source of the whine.

Hi William W. Plummer

Thanks for your reply

I stopped the fan for a moment with a bit of rolled up paper. The whine was
still audable. I know what you mean about the bearings though. I've even had
a PSU that had bearings that "ticked and clicked". lol.

Scotoma

 

[Paul Hopwood]

It was just a very uneducated guess that it was the capicitors.
I will try a higher rated PSU.

Better still, try a better quality PSU. A good 300W should be more
than sufficient for your system.

--

 

[kony]

My board that I posted about a while ago came back fixed

It turns out not only were 3 caps failing, one in a big way, but one of them
was also fitted the wrong way round when the board was made! Which might go
some way to explaining the failure, and the fact the board always made some
interference type noises.

It'll have cost me about a tenner to get it fixed though, so no point
chasing anyone up over it. Just surprised a Chaintech board was put together
like that.

??? Chaintech is a low-end brand, would be as or more likely to have such
problems.