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geekhack Community => Off Topic => Topic started by: tp4tissue on Thu, 10 July 2014, 05:50:16

Title: Electricity, WHY!
Post by: tp4tissue on Thu, 10 July 2014, 05:50:16
swapped  1of 2  1600uf 6.3v cap (blown) with 1800uf 6.3v cap (united chemicon)

voltage drop across cpu by 0.04 v


what's up with that? ne xperts on this?

(http://a.deviantart.net/avatars/k/y/kyleoniplz.gif?1)
Title: Re: Electricity, WHY!
Post by: Oobly on Thu, 10 July 2014, 08:04:58
It depends.
Title: Re: Electricity, WHY!
Post by: agodinhost on Thu, 10 July 2014, 09:26:12
Quote from: tp4tissue on Thu, 10 July 2014, 05:50:16
swapped  1of 2  1600uf 6.3v cap (blown) with 1800uf 6.3v cap (united chemicon)

voltage drop across cpu by 0.04 v


what's up with that? ne xperts on this?

Show Image
(http://a.deviantart.net/avatars/k/y/kyleoniplz.gif?1)

caps type?
kinda basic stuff - not sure if you know: some of then have polarity - and you should obey this polarity, then most probably you inverted your caps ...
Title: Re: Electricity, WHY!
Post by: tp4tissue on Thu, 10 July 2014, 09:33:20
Quote from: agodinhost on Thu, 10 July 2014, 09:26:12
Quote from: tp4tissue on Thu, 10 July 2014, 05:50:16
swapped  1of 2  1600uf 6.3v cap (blown) with 1800uf 6.3v cap (united chemicon)

voltage drop across cpu by 0.04 v


what's up with that? ne xperts on this?

Show Image
(http://a.deviantart.net/avatars/k/y/kyleoniplz.gif?1)

caps type?
kinda basic stuff - not sure if you know: some of then have polarity - and you should obey this polarity, then most probably you inverted your caps ...

LOL, i'm not thattt n00b... (http://emoticoner.com/files/emoticons/onion-head/uhuhuh-onion-head-emoticon.gif?1292862523)
Title: Re: Electricity, WHY!
Post by: dorkvader on Thu, 10 July 2014, 10:17:55
Quote from: agodinhost on Thu, 10 July 2014, 09:26:12
caps type?
I assume the blown cap was a normal aluminium electrolytic. The "united chemi-con" caps are all organic polymer electrolytic types.

What sort of voltage regulation is the MB supposed to have? failing caps can often play hell with that, as they present a different load.


Title: Re: Electricity, WHY!
Post by: tp4tissue on Thu, 10 July 2014, 10:29:18
Quote from: dorkvader on Thu, 10 July 2014, 10:17:55
Quote from: agodinhost on Thu, 10 July 2014, 09:26:12
caps type?
I assume the blown cap was a normal aluminium electrolytic. The "united chemi-con" caps are all organic polymer electrolytic types.

What sort of voltage regulation is the MB supposed to have? failing caps can often play hell with that, as they present a different load.




This seems to be the filter cap for a supplementary power input for the motherboard, they often did this before 8pin.

But I don't understand why the replacement cap is causing a voltage DROP?   
Title: Re: Electricity, WHY!
Post by: dorkvader on Thu, 10 July 2014, 10:36:40
Quote from: tp4tissue on Thu, 10 July 2014, 10:29:18
Quote from: dorkvader on Thu, 10 July 2014, 10:17:55
Quote from: agodinhost on Thu, 10 July 2014, 09:26:12
caps type?
I assume the blown cap was a normal aluminium electrolytic. The "united chemi-con" caps are all organic polymer electrolytic types.

What sort of voltage regulation is the MB supposed to have? failing caps can often play hell with that, as they present a different load.




This seems to be the filter cap for a supplementary power input for the motherboard, they often did this before 8pin.

But I don't understand why the replacement cap is causing a voltage DROP?   

I'm no EE, but my guess is because the ESR is much lower on the new cap. Power supplies are very complex beasts with respect to their loading. A lower resistance load can cause output voltage to be higher or lower, heavily dependant on the PSU design.

I'm sure a real engineer will know more: My experience is mainly with linear regulated PSUs and not with fancy modern motherboard power management.
Title: Re: Electricity, WHY!
Post by: tp4tissue on Thu, 10 July 2014, 10:41:14
Quote from: dorkvader on Thu, 10 July 2014, 10:36:40
Quote from: tp4tissue on Thu, 10 July 2014, 10:29:18
Quote from: dorkvader on Thu, 10 July 2014, 10:17:55
Quote from: agodinhost on Thu, 10 July 2014, 09:26:12
caps type?
I assume the blown cap was a normal aluminium electrolytic. The "united chemi-con" caps are all organic polymer electrolytic types.

What sort of voltage regulation is the MB supposed to have? failing caps can often play hell with that, as they present a different load.




This seems to be the filter cap for a supplementary power input for the motherboard, they often did this before 8pin.

But I don't understand why the replacement cap is causing a voltage DROP?   

I'm no EE, but my guess is because the ESR is much lower on the new cap. Power supplies are very complex beasts with respect to their loading. A lower resistance load can cause output voltage to be higher or lower, heavily dependant on the PSU design.

I'm sure a real engineer will know more: My experience is mainly with linear regulated PSUs and not with fancy modern motherboard power management.

why would lower resistance cause a voltage drop..   (http://emoticoner.com/files/emoticons/onion-head/confused-onion-head-emoticon.gif?1292862495)

because this is input stage..   shouldn't i get More voltage due to the current flowing more smoothly through?
Title: Re: Electricity, WHY!
Post by: Oobly on Fri, 11 July 2014, 06:18:45
It could also be the cap is doing a better job of smoothing ripple and the sensors see the less noisy supply as being at a lower overall voltage.

Or that it has more reserve so it gives a more stable supply, lower at low loads, but higher at high loads and you're measuring it at low load....

There are too many factors in the design of the supply and sensors to be able to tell without getting a full circuit diagram and knowledge of how the sensing is being done.

If it's less stable at the same speeds than it used to be then it could really be a lower voltage, but if it is as stable or more with high loads on, then it's just doing a better job.

My advice: Ignore the actual voltage reading compared to the old one and perform OC'ing, temp measuring and stability testing the usual way. It's likely to be giving you more voltage stability and less ripple than the old cap.
Title: Re: Electricity, WHY!
Post by: metalliqaz on Fri, 11 July 2014, 06:36:51
How are you measuring?
Title: Re: Electricity, WHY!
Post by: agodinhost on Fri, 11 July 2014, 06:45:36
Quote from: dorkvader on Thu, 10 July 2014, 10:36:40
I'm sure a real engineer will know more: My experience is mainly with linear regulated PSUs and not with fancy modern motherboard power management.
A "real" engineer would make you fall sleep after one hour of talk ...
Title: Re: Electricity, WHY!
Post by: tp4tissue on Fri, 11 July 2014, 07:13:47
Quote from: metalliqaz on Fri, 11 July 2014, 06:36:51
How are you measuring?

I didn't measure..

I changed out the blown cap with the close replacement on hand,  and with the same motherboard settings,  I see a cpu voltage drop of 0.04v

I also find it weird that ONE cap could cause this..  and this cap is NOT a main filter..