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**Topcat** · 07-11-2004, 02:41 AM

Hi and welcome to the boards!

First off, I must say that the board with the caps rigged and taped to the back of the PCB is one of the most ghetto/ricey installs I've seen to date!!

Modding such as that is not advisable unless you really know what you're doing.

The board you posted for example:
If you run caps in parallel, the capacitance value is either reduced or unchanged, depending on what values the combo is. (Example: a 2200uF and a 1500uF cap are placed in parallel. You add the two values together then divide it by 2. This would actually reduce the capacitance to 1850uF, which would not help anything. If you paired two identical value caps in parallel, the capacitance value wouldn't change.) However, the series resistance of caps in parallel is reduced half. This could be deadly for the motherboard, and most definitely not recommendable!

If the caps are placed in series, the capacitance value will double. (Example: 2x 2200uF 10v caps in series will yield a 4400uF 20v bi-polar cap) Whether that would help or hinder is dependent on the design specs of the circuit. For a VRM circuit, a little more capacitance will aid in filtration, but will not really help in overclocking stability. In most overclocking ventures, the CPU and RAM are the inhibiting factors, not the motherboard.

However, if your board has known crappy brands of caps, recapping with the same values, but high-end caps WILL help in reliability and in many cases help in overclocking. Crappy caps leave noise and worthless garbage on the power rails. For obvious reasons, this can cause instability. If that noise is eliminated by good quality caps, it will do nothing but help in perfoemance and reliability. I hope that answers those questions!

Feel free to post any electronics/computer related question you have on this board. There are some knowledgeable people in here, so it'll most likely be answered accurately.

**Kako** · 07-18-2004, 09:31 PM

To the left of the northbridge, their are 6 large mosfets, 3 to the top, 3 on the bottom. The way it works, is it a capacitor to each mosfet? or do three of the caps ontop of the choke coils have nothing to do with the mosfets? I know its difficult to look at this without any graph or board infront of you, but from general board layout design, what do you guys thing?

The ones on the top are 6.3v 3300uf, on the bottom, 16v 1500uf. If it is true that all 6 are to serve the same purpose, any reaason why they are of different values, or just to save a few bucks?

ps. I'll try to get a close up shot of that area to clear things up

**kc8adu** · 07-19-2004, 07:04 PM

caps in paralel add.ie 2 2200=4400
in series the voltage adds and 2 2200@ 10v would be 1100@20v.

**Topcat** · 07-20-2004, 07:46 AM

Originally posted by kc8adu

caps in paralel add.ie 2 2200=4400
in series the voltage adds and 2 2200@ 10v would be 1100@20v.

You sure about that? I read what I posted out of one of my old text books from back in the day...

**kc8adu** · 07-20-2004, 07:47 PM

im sure.
wont be the first big fsckup found in a book

the worst one i remember in hs was an auto shop book telling how to determine engine problems by wet/dry compression tests.
it stated if you got a increase in the reading after adding the oil the valves were bad.
and we all know its the rings.
busted out laughing in class when i read it.
teacher collected the books and got some others.
he found about 10 other goofs.

**kc8adu** · 07-20-2004, 07:52 PM

i doubt that ghetto rigged mess will work better than stock.
to see if more capacitor or replacement is in order just look for hash on the output of the vrm's.
bigger caps may give you a bit more on the overclocking side.
esp since the bean counters shave every fraction of a cent they can as long as it just works well enough to pass final inspection.

**Kako** · 07-23-2004, 03:00 PM

If I was to recap this area, what would be the best cap values to replace them with?

Thanks topcat for the hosting

I think I'll be making a cap purchase from you soon TopCat, just want to feel more comfortable with what shall be done and replaced with. The first post, the modder added to the other side of the board, the 6.3v/3300uf with 16/4700uf and the 16v/1500uf with 16v/2200uf. Are these acceptable values for me to replace the current caps with?

Also, Im going to need a decent soldering iron do this job. Will this one be ok: http://mcm.newark.com/NewarkWebComme...jsp?id=21-3475

This was posted on a audio forum, so kept the link for a possible future purpose. Its a 5-40w Iron. Any good ?

**Kako** · 07-26-2004, 10:59 AM

A long weekend for everybody. Enjoy iit guys.

**noorman** · 07-27-2004, 08:58 AM

Originally posted by Topcat

Hi and welcome to the boards!

First off, I must say that the board with the caps rigged and taped to the back of the PCB is one of the most ghetto/ricey installs I've seen to date!!

Modding such as that is not advisable unless you really know what you're doing.

The board you posted for example:
If you run caps in parallel, the capacitance value is either reduced or unchanged, depending on what values the combo is. (Example: a 2200uF and a 1500uF cap are placed in parallel. You add the two values together then divide it by 2. This would actually reduce the capacitance to 1850uF, which would not help anything. If you paired two identical value caps in parallel, the capacitance value wouldn't change.) However, the series resistance of caps in parallel is reduced half. This could be deadly for the motherboard, and most definitely not recommendable!

If the caps are placed in series, the capacitance value will double. (Example: 2x 2200uF 10v caps in series will yield a 4400uF 20v bi-polar cap) Whether that would help or hinder is dependent on the design specs of the circuit. For a VRM circuit, a little more capacitance will aid in filtration, but will not really help in overclocking stability. In most overclocking ventures, the CPU and RAM are the inhibiting factors, not the motherboard.

I have to correct you here !

If you place 2 caps in parallel you will get a capacitance of the sum of the 2 capacitances; so 2.200uF + 1.500uF will yield 3.700uF !!!
Best use the same working voltage, not lower, not higher (why ? ; this would be a long story, too long ...)

If as you say, you put 2 caps in series - your example being 2x 2.200uF/10V - you would get a bipolar cap of 1.100uF/20V !!!

The rules for CAPS are NOT the same as they are for resistances !

I should know, being an Electronics expert with over 25 years of experience; I 've worked in R&D and production control and did a course specificly for R&D in electronics ...

So, Kako has done well in placing parallel caps on his board.
This means, though, that his rush-in currents will be a lot higher than before; these will have to be delivered by his PSU (when starting up his PC only, of course).

More capacitance is good, but as I just explained, there are limits.

In my AUDIO system, that I developed and made myself, I have very high capacitances, but I limited the INRUSH currents by putting a low value (power) resistor in series with the MAINS input to the Transformer of the Analog regulated Power Supply that is being Short-Circuited by a relay contact when the PSU D.C. output voltage is high enough to activate that relay ...

8)

**Topcat** · 07-27-2004, 03:40 PM

As I mentioned, I pulled that info from an erronious text... It's been almost 15 years since I've been in electronics 101. I've had years of experience in the electronics service field, but this particular knowledge was never essencial in the service field, whereas it would be in an R&D environment. :oops: I looked into a more reliable source, and yes, you and KC8 are correct.

As for butchering up that board, sorry... We'll disagree on that... That was bad... If you want to increase the capacitance, don't solder caps to the bottom of the board. DO IT RIGHT and remove the original cap and install a higher valued cap in its place.

Obvious reasons and common sense says not to use a lower voltage cap when replacing caps... However, I've used 16v and 10v caps in place of 6.3v caps on hundreds of occasions, NEVER having had an adverse affect or failure from doing so. I can understand not getting carried away when increasing the voltage... Using caps rated at extremely high voltages can cause heavier current draw to charge, thus cause stress or overload. Although, the mild increases I mentioned are not enough to cause this. A slight increase in the voltage rating will not harm anything. I have even seen the MANUFACTURERS do this on motherboards. Example: I received a latter revision VP6 with EC 30 and EC31 using 470uF 25v caps, when the originals were only 16v. If you disagree with this, explain.

Feel free to explain why slightly increasing the voltage rating will kill a motherboard, please terms that the average reader will be able to understand.

Kako,
If I were going to change the cap values of the ones you mentioned... HMM... From past experiences, I would leave the 3300uF caps as they are. However, I would replace the 1500uF caps with 2200uF caps. This has shown benefits on a couple boards I tried it on, and I can say I've never seen adverse affects.

**kc8adu** · 07-27-2004, 07:05 PM

using higher voltage caps wontg hurt anything.
if you take it to extreems the cap will lose its form and may not work well.
as for higher capacitance as long as the vrm componants can take the inrush to charge them up no problem.
btw the relay/resistor setup is used in lots of other stuff with big caps that present a near short till they charge.see this in cnc motor drives.
another advantage to the bigger caps is the ability to ride thru glitches.

**noorman** · 07-28-2004, 09:13 AM

Originally posted by kc8adu

using higher voltage caps wontg hurt anything.
if you take it to extreems the cap will lose its form and may not work well.
as for higher capacitance as long as the vrm componants can take the inrush to charge them up no problem.
btw the relay/resistor setup is used in lots of other stuff with big caps that present a near short till they charge.see this in cnc motor drives.
another advantage to the bigger caps is the ability to ride thru glitches.

Using higher voltage caps won't hurt the component, but electrolytic caps need to be at or near their working voltage to 'produce' the capacitance value that is 'nominal' in the data sheets. So if you go way above what 's needed, the capacitance installed won't be the one that is printed on the component, but a lower value!

The working voltages of the caps on the mobo's usually are well over the voltage that they 'take' while working on that board!
So, you don't need to raise that voltage once more (to make sure); just put some 'good quality' components on the board with the same working voltage as the original(s).

If you want and can (diameter restrictions), you might increase the capacitances, but I would only go for an increase of about max. 50% to keep the inrush currents in check.

**Kako** · 07-30-2004, 09:37 PM

TopCat, you have pm.

**Kako** · 08-02-2004, 10:55 AM

Is this what I would need for 4700uF Rubycon caps?:

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=3827376160

If they are, leave me some guys 8)

**noorman** · 08-02-2004, 11:23 AM

Originally posted by Kako

Is this what I would need for 4700uF Rubycon caps?:

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=3827376160

If they are, leave me some guys 8)

the caps you found are 16V, not 10V like most are (or even 6.3V).
this means they are even bigger than the 10V types !
4.700uF will be larger too than 2.200uF !
in most cases, you 'll need caps with a max. diameter of 10mm !!!
in practically all cases, the max. diamater of 10mm means a max. capacitance of 2.200uF at 10Volts (and this only for the best makers & the specialist series/ miniaturized) !!!

**Kako** · 08-06-2004, 05:35 PM

Is it the cylinder we measure, or the "legs" of the cap? Sorry, whats the proper term for the "legs"?

**Topcat** · 08-06-2004, 06:12 PM

The gap between the legs/leads is the lead spacing. Mikee, I don't wanna hear your perverted comments about the above statement...

**Kako** · 08-06-2004, 06:46 PM

So when people say they need 8mm or 10mm replacement, they are talking about the lead spacing then?

**Topcat** · 08-06-2004, 08:07 PM

When they refer to 8mm or 10mm replacements, that's the diameter of the cap.

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