info needed on 8800GTS g92 Cap and other mods

[Vivi]

Heya, ive not seen any 8800gts 512's with a cap mod, maybe its not needed at all, but i would like to give it a try, very keen on trying ANYTHING to get my core up.
Could someone advise on which caps to use and where. i will mesure anyware you would like me to.
Pic by t_M (sorry for stealing!)
http://img.photobucket.com/albums/v310/T_M/G92-8800GTS-vMods.jpg
and here is a guy who modded his 8800gt with caps, Cryptik
scroll down to pics
http://www.xtremesystems.org/forums/showthread.php?p=3660365

Thanks appreciate it, ALSO if you have any other kind of strange mod u want me to try i will do it, i want to do every mod possible on this card til there is no more pcb left to solder on.

Thanks

[CryptiK]

In this pic I have shown where it is possible to add caps in parallel into the circuit for the core & shader voltage supply on the back of the card. If you can take a pic of the front of the card I can indicate where you can add more caps there too. I would not advise adding a cap to every position as this will more than likely be too much capacitance, but 2 caps per phase on the input side (16v caps) and 1 - 2 caps per phase on the output side (12v caps) should be fine and perhaps give you a gain in core/shader speed.

With the 16v input side caps just double check the polarity of the surface mount caps before soldering to them but I'm pretty sure the the way I have annotated it is correct (oe: red point should measure at ~12v when card is powered on).

Regarding cap selection, choose low ESR high ripple current caps of around 1500uf - 2200uf capacitance. Blackgate caps are the best but very expensive and hard to get hold of, so in lieu of that, Rubycon MCZ, Panasonic FM, Rubycon MBZ, Sanyo WG, or Rubycon ZA caps will do fine.

http://i720.photobucket.com/albums/ww206/CryptiKone/G92GTScapmodpoints.jpg

[Vivi]

excellent i will get working on that :)! and post pics + results later

Il get you a pic asap today of inside of card.

Thanks allot for the paint effort you put in to this!

[Vivi]

Here what ive done so far,

http://img255.imageshack.us/img255/9039/43239616.jpg

Here pics you requested. sorry my card looks dirty ;p
http://img255.imageshack.us/img255/7715/61335871.jpg

http://img255.imageshack.us/img255/5293/66260360.jpg

http://img255.imageshack.us/img255/3134/79105246.jpg

[K404]

GO Cryptik! :D

Goddy...what I said in the PM was kinda wrong. I said "soldered in parallel to the first cap (input side) of each PWM phase."

I mean...the input of the output :p: Cryptik is right. The first cap is probably the best one to mod to deal with any spikes.

[Vivi]

Aah luckily for cryptic :D, but your motherboard modding skills i will need again for sure! and hope to see you in taipei if you make it right?! gonna be sick!!
this card's core does 830 modded on stock air and 855 cold water with mod, (19c on card) so im hoping at -190 i can throw it with volts without OCP, but if you said the ocp gets kind of countered by cold i will try get that spot cold aswel.

OT ON MOTHERBOARDS: Also, i see most caps have "-55c" on them, does this mean if you have a huge pot and it basically freezez all the 2.5v caps around the cpu area that you might get lower performance or lower cpu speeds? cause i've seen a pot on a system with the cpu getting 6.2ghz, and the EXACT same system with bigger pot scraping the caps not even getting 5.8 stable, could it be?

[K404]

its entirely possible. It depends on how the caps fail at low temps. A heating element around the caps could help and shouldnt hurt CPU temps. Shouldnt increase the risk of condensation either.

Did you not see? Benchtec didnt even make it to the euro finals. We had a **** CPU to start so we lost the Pi section pretty badly.

Euro finals have GPR and Hipro amongst other big names LOL The only way they're getting beaten is through really bad luck on their part and really good luck on someone elses :D

[Vivi]

hahaha ok :D
Damn man i thought i saw your name somewhere saying your going through, but now i remeber you said your cpu was baaaaad.

I have to been you sometime.. Aoc moa? :D

I have to meet* you sometime.. aoc moa? :D (is what i meant to type, dont know why i said been? rofl)

[K404]

lol continuing the O/T...Whats the AOC MOA? :)

[celemine1Gig]

BTW, what caps are you going to use?

I would probably add some ceramic caps (100nF X7R and NPO for high frequency noise) on the backside and some polymer caps(for the lower frequency noise), parallel to the tantalum ones on the frontside. ;) but don't overdo it in terms of capacitance. Remember that the card already has enough capacitance to work alright. You just want to improve it a bit. Too much capacitance could be bad.

[T_M]

Did you consider inductor mods?

[Vivi]

Did you consider inductor mods?

could you explain abit more about this? I would love to find out and try it, you are my modding idle since the day i saw tha 9800gx2 of yours in taipei :)

[celemine1Gig]

In short and simplified, inductors block out high frequency "noise". On your motherboard you have mosfets, fed with 12V, that switch in high frequency to be able to deliever the high currents at a certain voltage (VCore here) that are needed by the CPU. The switching is used because it is a more efficient way than using linear regulation. The high frequency output is then smoothed out by capacitors and then there are a row of inductors to block out the unwanted high frequency portion of the signal that is still left from switching. The inductors have a value in Henry [(V*s)/A] which defines the frequency that they are going to block out and/or pass through. That's why you should not change that value if you don't know exactly what you are doing. What you can do is to get inductors that can stand a higher current value.

Keep in mind that if you add caps in parallel, capacitance increases, but for inductors it's different(see the text above and the links below):

http://www.allaboutcircuits.com/vol_1/chpt_13/4.html
vs.
http://www.allaboutcircuits.com/vol_1/chpt_15/4.html

[CryptiK]

Yes higher current rating inductors may also be of some benefit, the ones from old motherboards have been used by people previously - they need a bit of heat to remove and solder on but if you have some dead boards lying around you can harvest the inductors. You will need 3.

The pics of the front of the card are a bit close up, if you could take one pic that captures the whole back end of the front of the card that would be perfect.

Here's the 2 pics showing the cap mod points (phase output side) and the mosfets that need heatsinks added. Three groups of three mosfets are for the vgpu and 3 mosfets are for the memory power phase. I can put everything on one pic to make it clearer if you can take a large one that shows the whole back section.

For the ceramic caps that you can add electrolytic caps too, you will need to find out which side of the component is positive by using a DMM. Using DC voltage setting (20v) stick the black probe in one of the 2 earths of a molex plug (2 black wires in the middle of the molex) and probe each side of the caps with the red probe - one side should read 0v (earth) and the other side will read whatever the vgpu is set to. When you add electrolytic to the ceramic caps, the positive side of the electrolytic cap goes to the positive side of the ceramic cap.

http://i720.photobucket.com/albums/ww206/CryptiKone/g92cardfrontcappositionscopy.jpg

http://i720.photobucket.com/albums/ww206/CryptiKone/g92cardfront3.jpg