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My first Vmod, Help Please :)

post #1 of 16
Thread Starter 
I received this "dead" 8500 gt from work.. Replaced the broken caps with some off of an old motherboard, They are the same capacitance ( 1500 uf ), but higher voltage ( 10v > the stock 6.3v ).. The card works now.. But I feel as if I have already done something wrong lol. I want to beef this card up a bit, and drop some scores on the bot with it.. That is if I can even get this thing functional after modding it, I will try this with my 8600 GT and so on .. So to start things off. Some pics of the card smile.gif





I am reading thru the vmod essentials thread now. I guess I am just looking for general advice about this card specifically , anything I might have done wrong already, etc. ... Thanks in advance

Some better pics of the umm , chips I know you guys always ask to see lol..




Edited by Capwn - 4/8/13 at 2:38pm
post #2 of 16
The Vcore and the Vmem are likely both controlled by the chips labelled 6549CBZ. Looking at the datasheet it looks like a variable pot on Pin 4 to ground will change the voltage. You can likely check the voltage on the legs of the caps but someone else will have to help you with which size of pot to use and where to measure the resistances to fill in the equation that will tell you.
    
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post #3 of 16
Did some more checking and perhaps your card is alot like the 8600 GT. Maybe check out this article. Looks like 20K pots might do the trick, but thats just my guess and maybe someone else can confirm.
    
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post #4 of 16

does look like a 8600 .. measure stock resistance using the same guide and see if 20k seems reasonable..

 

*looks like GPU has grounded out a couple times huh..? got Burn marks..?

post #5 of 16
Thread Starter 
It is a 8500 GT, Its printed right on the PCB in the first set of photos there, as well as on the sticker from inno 3D, As for the burn marks, Im still new at soldering, Card still works fine..
Did anyone notice my question about the capacitors I used ?
post #6 of 16
Caps are fine.. you can up voltage and farad rating without negatively affecting most gpu circuits.

*if you are pushing high speeds.. go for a higher quality cap with increased farad rating for better filtering.

*adding a higher voltage cap will not always store or add additional voltage beyond what the input supply is.. so increasing farads may be more helpful for OC.
post #7 of 16
Thread Starter 
Quote:
Originally Posted by CL3P20 View Post

Caps are fine.. you can up voltage and farad rating without negatively affecting most gpu circuits.

*if you are pushing high speeds.. go for a higher quality cap with increased farad rating for better filtering.

*adding a higher voltage cap will not always store or add additional voltage beyond what the input supply is.. so increasing farads may be more helpful for OC.

Right on, I used some Sanyo caps I pulled frrom an old motherboards CPU area ( only used them because it was the only ones I had in the house even close to the og caps. ). I will see if Pizzaman will take a look at her this weekend at teh ln2 meet..

But to continue with what you are saying, I can add one or two more caps to the existing ones and it will help with stability when I start pushing voltage? Okay, Next can somebody show me where to what points on the card to measure? Also what parts I need to pick up ( VR wise.. ? )
post #8 of 16

Red = vmem

Yellow = GPUv

Blue = input voltage.. 12v

 

 

 

positive on GPUv and vMEM.. the input spots i labeled - you should check just to make sure.. i cant make out the voltages on the caps in the front-side pic.. but from the looks of the 'flow' they should be 12v input.

 

*You can "piggy-back caps" onto the legs of the existing caps if you need to bolster voltage a bit more on the GPU.. I would add an input cap for mem and GPUv to start with.. but you really need to test voltage stability under load conditions to "see" what the PCB really needs you to add.

 

 

**for VR - you need to measure at the mod-point for resistance to see what size VR is required [just to be safe].. make sure to document your stock resistance.. as its very helpful to know when troubleshooting.


Edited by CL3P20 - 4/9/13 at 10:20am
post #9 of 16
Thread Starter 
Quote:
Originally Posted by CL3P20 View Post

Red = vmem
Yellow = GPUv
Blue = input voltage.. 12v





positive on GPUv and vMEM.. the input spots i labeled - you should check just to make sure.. i cant make out the voltages on the caps in the front-side pic.. but from the looks of the 'flow' they should be 12v input.

*You can "piggy-back caps" onto the legs of the existing caps if you need to bolster voltage a bit more on the GPU.. I would add an input cap for mem and GPUv to start with.. but you really need to test voltage stability under load conditions to "see" what the PCB really needs you to add.


**for VR - you need to measure at the mod-point for resistance to see what size VR is required [just to be safe].. make sure to document your stock resistance.. as its very helpful to know when troubleshooting.
The stock ones were 1500 uf 6.3 v. I replaced them with 1500 uf 10 v.. Does the gpu need to be installed and running to check these points?
post #10 of 16
If your checking resistance do NOT have it running or even installed. To measure voltages you must have it running.
    
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