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post #501 of 553
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Quote:
Originally Posted by madness777 View Post

Quote:
Originally Posted by michaelrw View Post

adding caps to a pcb is completely new to me and dont even know where to begin. what exactly needs to done? is this done with smd caps or the big through-hole style caps thar are cylinder shape?

You just need to know what uF caps you will use... most common for output are solid caps 820uF 2.5v, for 12v from 1000-3300uF 16v electrolytic caps...
When you solder them on you have to be careful you don't solder em the wrong way round... watch for + and -

 

 Actually reversing the "phase" of the cap can increase filtering or capacitance depending on how its put in-line with existing caps.

 

From what I remember:

 

 Adding caps in series [alternating +/-] = increased power filtering potential

 Adding caps in parallel [keeing +/- like-for-like] = increased current potential

 

**Various GPU's need combinations of both of the above.. some only one of the other .. mostly depending on the power phase design and cap choice/layout on the PCB.

 

 

 Regards,

post #502 of 553
Quote:
Originally Posted by CL3P20 View Post

 Actually reversing the "phase" of the cap can increase filtering or capacitance depending on how its put in-line with existing caps.

From what I remember:

 Adding caps in series [alternating +/-] = increased power filtering potential
 Adding caps in parallel [keeing +/- like-for-like] = increased current potential

**Various GPU's need combinations of both of the above.. some only one of the other .. mostly depending on the power phase design and cap choice/layout on the PCB.


 Regards,
I think what maddness is saying is that you don't want to mix up the polarity of polar caps (caps with +/- signs on them). Such that if there is a polar cap on the board, and you solder another polar cap to it (they will be in parallel) that the +/- must be the same orientation.
    
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post #503 of 553
^! Correct
post #504 of 553
i appreciate the help guys... but in all honesty this is over my head.
i dont quite understand it on a conceptual level, so its hard to use deductive reasoning to determine what caps i need, where to put them.. and more importantly what i am trying to accomplish (conceptually) and why

from college physics i know that capacitors store electrical energy by separating and storing charge and that the SI unit for capacitance is the Farad .. other than that i dont know much
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post #505 of 553
Well, it's explained in lots of threads. They just reduce ripple, thus increase core stability under high voltages and reduce load on the caps already on the card... Usually more caps with more uF mean more stability but not in all scenarios. From experience, 820uF is best for core/mem if you're using solid caps and 1000-3300uF electrolytic caps for 12v (CL3P20s info!), and not too much of them...

I'll put it like this... if you use 1 cap per phase on a 3 phase system (weak system! Like on a 8800GTS or even weaker 2 phase on a 8800GT) you'll gain 1/50 stability, 2 caps per phase 1/45, 3 caps per phase 1/42, 4 caps per phase 1/41, 5 caps 1/40 and so on... Am I clear?

So you won't gain A HUGE amount of stability if you keep putting caps on it... So you have to try to put on the optimum amount of caps...

Where to put them? Find the spots of the input and output phase, find where the ground pin is and what voltage it's at (just for safety precautions) and solder a desired value cap on... we can help aswell... =]
post #506 of 553
Quote:
Originally Posted by madness777 View Post

Well, it's explained in lots of threads.
im notoriously bad at searching for and successfully finding threads for specific things like this. thanks for your patience smile.gif


Quote:
Originally Posted by madness777 View Post

They just reduce ripple, thus increase core stability under high voltages and reduce load on the caps already on the card... Usually more caps with more uF mean more stability but not in all scenarios.
ok cool, pretty straightforward i suppose


Quote:
Originally Posted by madness777 View Post

From experience, 820uF is best for core/mem if you're using solid caps and 1000-3300uF electrolytic caps for 12v (CL3P20s info!), and not too much of them...
what runs on the 12v rail? is it just like the "main" power line?


Quote:
Originally Posted by madness777 View Post

I'll put it like this... if you use 1 cap per phase on a 3 phase system (weak system! Like on a 8800GTS or even weaker 2 phase on a 8800GT) you'll gain 1/50 stability, 2 caps per phase 1/45, 3 caps per phase 1/42, 4 caps per phase 1/41, 5 caps 1/40 and so on... Am I clear?
yep, that makes perfect sense, thank you thumb.gif


Quote:
Originally Posted by madness777 View Post

Where to put them? Find the spots of the input and output phase, find where the ground pin is and what voltage it's at (just for safety precautions) and solder a desired value cap on...
How do I find the spots of the input and output phase? Am i looking for a particular smd? You mention finding the ground pin.. I assume youre talking about the ground pin on the voltage controller IC ??
for my first cap mod i will be doing a 8800GT, which is 2 phase. i assume each of those two phases has an input and output that i need to find?


Quote:
Originally Posted by madness777 View Post

we can help aswell... =]
thanks a lot, i really do appreciate it thumb.gif
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post #507 of 553
Sweet! An 8800GT! Here:
img1951.jpg

You can also put inductors over the stock inductors, they really help with the squeal under high load/volts! GT really has a weak power delivery so everything counts!
img1948.jpg

'Ground pin' as in ground on the spot where you're gonna solder on a cap. You need to solder it the right way... The colored part of the cap is -/ground. But you can already see on the card which side is ground.

12v is where the power connector is. Example:
img1948-12v.jpg
Edited by madness777 - 8/17/12 at 12:22pm
post #508 of 553
Quote:
Originally Posted by michaelrw View Post

adding caps to a pcb is completely new to me and dont even know where to begin. what exactly needs to done? is this done with smd caps or the big through-hole style caps thar are cylinder shape?

They need to be low esr caps they can be had from eBay cheap. I like to stick to either rubicon or nichon brand. The bigger the uF value the better. You can use all 16v caps if you want to be lazy but I suggest 6v for mem and core output and 16v for 12v input 2.5 caps are a pita to source
    
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post #509 of 553
Quote:
Originally Posted by madness777 View Post

Sweet! An 8800GT! Here:
img1951.jpg
You can also put inductors over the stock inductors, they really help with the squeal under high load/volts! GT really has a weak power delivery so everything counts!
img1948.jpg
'Ground pin' as in ground on the spot where you're gonna solder on a cap. You need to solder it the right way... The colored part of the cap is -/ground. But you can already see on the card which side is ground.
12v is where the power connector is. Example:
img1948-12v.jpg

ok cool. thanks for the nice pictures! most of that makes sense. let me see if i got this:
so the caps you added to the 12v area, it looks like theyre added on top of stock inductors..right?
then to the left of the 12v area, you added some caps to what looks to be smd caps, and inductors (the orange wire loop) on top of inductors.. am i seeing this right?

also, you said i can see on the card which side is ground ... where is it marked + and - ?? or can i somehow use a dmm to find which side is ground.

Thanks thumb.gif
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post #510 of 553
I added inductors over the stock Gray inductors, 2.5v caps on each side over the stock SMD caps... You can use the 'beep' function on the DMM to find ground... do you know which pins on the power connector are ground?

+ isnt indicated on the cap. Only - is... it's the colored part of the cap... You need to find ground on the card yourself... Easy
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