Modding the heck outta my 4850

[eligray]

Hey guys, I've been spending a lot of time modding my 4850 GPU. Until today, I had put it under very high performance water cooling,and put 2 fans blowing on its face. With these temps, I vmodded my GPU core. Today, I also soldered an extra 6-pin power connector onto the back of the card. Today, I also spent hours desoldering every single non-ceramic capacitor from my dead xbox360. I now plan to use these same capacitors to help stabilize the voltages around my graphics card. (EDIT: now thinking caps from dead 8800gt)

The question is: How many capacitors is too many and will make the startup power draw too large? I would like to solder a capacitor in parallel for each capacitor on the card. I will make sure it has at least the same voltage rating, and they will probably all have larger capacity than the stock ones. It looks like there will be 2-3 for stabilization of the 12v input, and 2-3 further down the line.

Thoughts/comments? :)

[Boogerlad]

I'm sorry that i can't answer your question, but I must ask you one. Where did you get the extra 6 pin power connector?

[CryptiK]

I think you could safely add ~1500uf - 3300uf to each phase input and 1500uf - 2200uf to each phase output. Going over that may be too much, but there isn't really any way to tell other than trying. I certainly wouldn't put a cap in parallel with every cap you have on the board, that will be adding too much capacitance. Also, what brand & model are the caps from your xbox? You want to be adding very high quality caps, meaning they need to be low ESR and have a high ripple current rating, adding low quality caps may make things worse than they are already, as circuits are tuned for a specific amount of capacitance and resistance.

[eligray]

I'm sorry that i can't answer your question, but I must ask you one. Where did you get the extra 6 pin power connector?

off my dead 8800gt *RIP*:(

[eligray]

I think you could safely add ~1500uf - 3300uf to each phase input and 1500uf - 2200uf to each phase output. Going over that may be too much, but there isn't really any way to tell other than trying. I certainly wouldn't put a cap in parallel with every cap you have on the board, that will be adding too much capacitance. Also, what brand & model are the caps from your xbox? You want to be adding very high quality caps, meaning they need to be low ESR and have a high ripple current rating, adding low quality caps may make things worse than they are already, as circuits are tuned for a specific amount of capacitance and resistance.

what do you mean by each phase input/output? The caps I imagine are not high quality, as a 360 really just needs to turn on. However, I have some caps on my old 8800gt that look like they may be up to the job. Let me go get the numbers off of them and a pic of their design.

Do you have any idea what extra returns could be expected if the mod was done perfectly with very high quality caps? Is something like 10-20mhz extra realistic on a 15% overvolt and 36% overclock? I'd imagine the benefits become more obvious as you push the card's limits further and further. The real point of this project is not just high speeds, it's also to get hands-on experience doing some of these more hardcore mods. BRB with those specs...

[eligray]

the capacitors on the 8800gt (there are six of them) each contain four lines, as follows:

748
SVP
180
16

I'll find a link of how they look. Metal shelled cylinder with purple line covering ~1/5th of top surface

[eligray]

finally found it

Its one of these two very similar models

www .endrich.com/en/site.php/109?productsearch=search&filter[title]=&filter[type]=&filter[seriesname]=SVP+&filter[num%3Avoltage]=16&filter[num%3Acapacitance]=180&filter[num%3Aresistance]=&range[num%3Aripple%2Cnum%3Aripple]=#resultlist

EDIT: remove the large space from after www from the URL, XS doesn't like hyperlinking this one correctly

[FragZero]

I can't help you but i've been thinking about the same thing. Cheapest 4850, HR03 GT + high cfm fan, Good VRM cooling, ram heatsinks , voltmod and extra high quality caps.

What are your results now ?

I had a HD3850 256MB @ 950 / 1000 1.52V with a accelero S1 and it outperformed any stock 3870 (including oc-editions) and most overclocked, non voltmoded 3870 . I'm only using a 19" 1280x1024 display though :p:.

But a 4850 + all the cooling mods costs about the same as a 4870, so i'm not sure if its a good idea.

[eligray]

I didn't actually spend a single cent on the cooling, its all left over from and compatible with my last GPU (the dead 8800gt)

I haven't done extensive OC testing, but totally stock, I had around 700-720 max core when stable. Vmodded and better cooling, I got somewhere from 840-870 core (didn't test thoroughly) at 1.4v when stable enough to pass 3dmark01. It's looking like I may be able to break 900 core benching 3Dmark on water. My memory is good to around 1240mhz, but I set back to 1230 when I had some stability issues, and all was well. It'd be great to surpass factory OC'ed 4870's. (hey, looks like I already did core-wise). Make that goal user-OC'ed 4870's.

As I said, it can't be a bad deal for me, I haven't spent a cent modding, and the only thing I could need to buy is if I go for really high quality caps.

[FragZero]

I didn't actually spend a single cent on the cooling, its all left over from and compatible with my last GPU (the dead 8800gt)

I haven't done extensive OC testing, but totally stock, I had around 700-720 max core when stable. Vmodded and better cooling, I got somewhere from 840-870 core (didn't test thoroughly) at 1.4v when stable enough to pass 3dmark01. It's looking like I may be able to break 900 core benching 3Dmark on water. My memory is good to around 1240mhz, but I set back to 1230 when I had some stability issues, and all was well. It'd be great to surpass factory OC'ed 4870's. (hey, looks like I already did core-wise). Make that goal user-OC'ed 4870's.

As I said, it can't be a bad deal for me, I haven't spent a cent modding, and the only thing I could need to buy is if I go for really high quality caps.


I think i'll start with a 4850 with a custom heatsink so it has a dedicated VRM heatsink, some ram heatsink, 2x pot, my S1 + fan and lets hope i can get 800 core 1200 ram on decent temps (i'm using it for 24/24).

[[XC] gomeler]

The HD4850 will get up to 900MHz and higher on the core :up: Don't be worried about feeding it a bit of voltage, just keep temps below 80C at load :up:

[FragZero]

gomeler;3587696']The HD4850 will get up to 900MHz and higher on the core :up: Don't be worried about feeding it a bit of voltage, just keep temps below 80C at load :up:

I know the 4850 can do high clocks, but i'm using 24/24h, not for benching :)

[CryptiK]

i know the caps you mean, I have an 8800GT too they're the same on mine. Personally I'd go for some high quality electrolytic caps, my personal favourites are Rubycon MBZ (now discontinued and replaced with MCZ series), Sanyo WG, and Panasonic FJ or FM.

Cap mods are something that need to be considered carefully, as the results can very easily be detrimental rather than beneficial. The size, ESR and ripple ratings of each added cap and the location of the cap need to be optimal for that circuit, and even if those parameters are satisfied, it still may cause negative results due to the nature of the circuit you are adding them too. The added capacitors legs also need to be very short, or it can cause problems.

When I said phase inputs/outputs I mean the input side and output side of each phase of the cards PWM circuity. I think there are 2 phases on your card, but I'm not certain of that. The input side will require the use of 16v caps, as they will be running at 12v, and the output side will require 6.3v caps (perhaps also 4v caps could be used but harder to find easily) as they will only be running at whatever the vgpu is set to.

You need to measure with DMM the voltage at the place where you want to add the caps, adding a cap rated below the voltage it will be run at will cause it to blow. You also need to add the caps in parallel, or there will be trouble. I do suggest you do a bit of reading about PWM circuits/caps/cap modding before attempting the mod, as there is a few things to consider.

The addition of phase output caps on my 8800GT reduced the vgpu required for 756MHz stable from 1.24v to 1.20v, however no gains for your card can be assured as each card/model is different. I only did it to my 8800GT to help take the strain off the mosfets as the 8800GT phases are weak and there is only 2 phases as opposed to the 4 phases of the G80 GTX/Ultra's.

Caps/coils mod is usually done in high voltage extreme cooling situations to help extract the last bit of performance out of the card, but gains from these mods are typically not large.

[[XC] gomeler]

Uhh.. mine was doing ~875MHz 24/7 for about 4 months until I retired it. That was on aircooling also ;)

[eligray]

gom: holy... that's truly impressive. I think I'd need to run my core off the 12v rail for that 80c you're talking about.

Cryptik: Thanks for the help. Those results you got on your 8800gt are really impressive, I didn't think a cap mod would do that much.

This is amazing, I just looked up those rubycon caps you mentioned, they look like they may be the ones from my 360. Gonna go check

[eligray]

the caps I have out of my 360 are rubycon mfz :shrug:

The list of caps I have:

8800gt caps (described earlier)
Rubycon 6.3v 2700uf MFZ
Nichicon 16v 100uf A0546
Nippon ChemiCon NCC KZJ 16V 1500UF "ULTRA LOW ESR" (pics and spec'ed HERE (http://cgi.ebay.it/ws/eBayISAPI.dll?ViewItem&item=300206736760&ssPageName=MERC_VI_RSCC_Pr8_PcY_BIN_Stores_IT&refitem=290259161870&itemcount=8&refwidgetloc=active_view_item&usedrule1=StoreCatToStoreCat&refwidgettype=cross_promot_widget&_trksid=p284.m184&_trkparms=algo%3DDR%26its%3DS%252BI%252BSS%26itu%3 DISS%252BUCI%252BSI%26otn%3D8#ebayphotohosting))
unbranded 10v 220uf KY
unbranded 4v 820uf bright yellow capacitor, 5053u with a "M" above it. Company logo is an F underlined and overlined.

Looks like the supposedly low ESR KZJ caps may be my best bet? If none are fitting, here (http://cgi.ebay.it/3-Rubycon-MBZ-6-3V-3300-UF-ULTRA-LOW-ESR-PC-Capactior_W0QQitemZ290289226730QQihZ019QQcategoryZ 4662QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l 1262) are some of your beloved MBZ caps, if a little large. I'd probably go MCZ though, it says "This is the Premium grade motherboard capacitor.MCZ series has achieved lower ESR at high frequency from conventional MBZ series by approximately 40%", they're here (http://cgi.ebay.it/6-Rubycon-MCZ-6-3V-1800-UF-ULTRA-LOW-ESR-PC-Capacitor_W0QQitemZ290289226825QQihZ019QQcategoryZ 4662QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l 1262)

Thanks for all the help!

[CryptiK]

The Rubycon MFZ 2700uf 6.3v caps appear to be OEM and used almost exclusively in xbox 360's. They have a very low ESR rating of 0.007 ohms but I cant find their ripple rating. They do based on their ESR appear to be nice caps, and if you already have them you may as well give them a go on the phase output side. The KZJ's also look good if you have them already they should do fine for the phase input side caps.

The Nichicon 100uf caps are too small to be worth adding. You'd need at least an 820uf cap, to buffer the ripple in the circuit. As for the no name caps, I would not use them, they are likely to have inferior specifications and will probably make you card worse if added.

The MBZ's used to be the best Rubycon caps, but the MCZ's superseded them. I still have some MBZ's so I use them but I'd buy MCZ's if I needed more due to the superior characteristics they posses.

The best caps based on specs are actually the Nichicon HZ's, they have a very high ripple curent and very low ESR, but if purchasing them you must make sure they are manufactured after 2005-2006. Before this there was an issue with nichicon where they were overfilling their caps which caused them to swell and leak well before they should have. This caused the deaths of many Dell optiplex and other motherboards that used them, as they were a very popular cap. If they are new ones though there is no problem with using them, some guys still shy away from them to the problems back in 2003-2004 but the new caps are fine.

[eligray]

The Rubycon MFZ 2700uf 6.3v caps appear to be OEM and used almost exclusively in xbox 360's. They have a very low ESR rating of 0.007 ohms but I cant find their ripple rating. They do based on their ESR appear to be nice caps, and if you already have them you may as well give them a go on the phase output side. The KZJ's also look good if you have them already they should do fine for the phase input side caps.

The Nichicon 100uf caps are too small to be worth adding. You'd need at least an 820uf cap, to buffer the ripple in the circuit. As for the no name caps, I would not use them, they are likely to have inferior specifications and will probably make you card worse if added.

The MBZ's used to be the best Rubycon caps, but the MCZ's superseded them. I still have some MBZ's so I use them but I'd buy MCZ's if I needed more due to the superior characteristics they posses.

The best caps based on specs are actually the Nichicon HZ's, they have a very high ripple curent and very low ESR, but if purchasing them you must make sure they are manufactured after 2005-2006. Before this there was an issue with nichicon where they were overfilling their caps which caused them to swell and leak well before they should have. This caused the deaths of many Dell optiplex and other motherboards that used them, as they were a very popular cap. If they are new ones though there is no problem with using them, some guys still shy away from them to the problems back in 2003-2004 but the new caps are fine.
Thanks you SOOOO much. I'm going to test the card's max OC at 1.4v before adding the caps, then I'll report back so others can see if it provides a noticeable benefit. Thanks again :)

[eligray]

816 was my max core before mod, with only one power plug in. I'll have to solder the caps onto the back tomorrow.

[CryptiK]

No problem, good luck with it. Hope it goes well.

[eligray]

Well, I don't have much to show for all the work I did

Max clock that passed '06 before was 816, afterwards, I passed at this same speed, but failed at 823. No real gains :shrug: This is with three phase input caps, three phase output caps.

[CryptiK]

I guess that just comes down to the individual card. Cap mods don't usually give large gains, and since you cant increase core clocks in increments of 1MHz, its hard to tell if there was any gain at all. Often going up to the next step is just too far.