Sparkle 8800gt Voltmod - no reference design?!

[Heinzkopf]

hi there,
i wanted to volt mod my sparkle 8800gt but while comparing it to the g92 standard pcb design i doubt whether it's possibile to mod it at all.

Can some1 with a sparkle 8800GT show me the measuring points of vGpu and where to put the resistor??

thanks

[HitandRun]

How about posting some close up pictures so we know what we dealing with!

[Heinzkopf]

Hi,
yea sorry I forgot to take some

Here are 2 pics of my Sparkle 8800GT with (slightly modified) Artic Cooling Accelero S1- had to make it fit into my case:






The original Cooler was this one:



Background is I want to overclock the card as much as possible,
with BIOS vmod i only could change the vGPU Load to 1.1V which allowed me to set the GPU to 680Mhz.
1Mhz more and i have artifacts.

With the accelero (and 120mm fan blowing) the temperature doesnt exceed 50°C- so i have much space for higher voltages

First it would be nice, if someone could show me the + measure Point of vGPU Voltage. That i could check the actual vGPU (must be 1.1V) and see if the BIOS accepts higher voltages than 1.1V (i dont think so, because with 1.17V set to BIOS i didnt achieved better OC results.. so it must still stay to 1.1V)

BIG THX and sorry for my bad english

[largon]

vGPU can be found from these red points - possibly also vMEM (which would be the one farthest from PCIe connector) but I can't be sure since the HS completely blocks the frontside pic.


The highlighted chip, what's the label on it?

[Heinzkopf]

Hi,
the chip's label should be
L6713A
990TS VH
MYS 99 729
(but u can read it now on the pics below)


Here are some more detailed pics of the front with heatsink removed:






And here of the back, especially from the areas that may have sth to do with voltage





Sorry for the big filesize, but i didnt change the resolution because I think the more information u get the better u can help me

I tried to measure the vGPU with the red dots u pointed to- well i got the result of 1.8V (!) -
Did i do sth wrong´?! i connected the black cable of my multimeter to the case (which should be ground?!) and then put the red on the dot on the picture..
(I get this 1.8 Value on every big red Pin u showed me..)(

[largon]

Something funny going on with the measurements. They can't all measure the same... (unless your vGPU is @ 1.8V that is)
After seeing the frontside I can confirm that the legs of the large black block-like part (inductor) that reads "1R5M" is vMEM, it's the one farthest from the PCIe connector. Legs of "R33M" is vGPU.

[HitandRun]

Something funny going on with the measurements. They can't all measure the same... (unless your vGPU is @ 1.8V that is)
After seeing the frontside I can confirm that the legs of the large black block-like part (inductor) that reads "1R5M" is vMEM, it's the one farthest from the PCIe connector. Legs of "R33M" is vGPU.

1.8V sond like the volt mod is done! He He!

[Heinzkopf]

Hi, well it was my mistake

I measured the voltage of the part (looks like capacitor) below 1R5M and there was ~1,8V.


R33M is 1,1V in IDLE and 1,07V in LOAD
1R5M is the same- either vMEM is the same or 1R5M is also responsible for vGPU

(But vMem isnt interesting for me anyway- i can clock the Mem to 1030 without errors, that's not the problem..RAM doesnt improve performance that hard)

Well good to measure the vGPU.
I set the vGPU to 1,17 with nibitor- so it's correct that u can't set a higher value than 1,1V with BIOS.
And that my card comes with ~1,05V by standard


But the 680Mhz with 1,1V arent that good- so wouldn't it be nice to take the next step:
increasing the vGPU by resistor

It would be nice if someone helped me

[largon]

- measure resistance between either of these points marked in red AND GROUND
- multiply the measurement result by 20
- use a VR rated at about the final result (measured_resistance × 20)

[blind_ripper]

will try that later today , also i need to find the vgpu read-out point .
if some1 give more in put on the card's lay-out

[Heinzkopf]

@largon
Do I have to measure the resistante between those two points or of each point to ground?
If it is between each point and ground and the result differs from each other, which variable resistor do i have to take then?

And where to put the resistor between? (for increasing vGPU)

Thank you

[largon]

Whoops, I forgot to type "AND GROUND" in the end of the line

- measure resistance between either of these points marked in red

It doesn't matter which point - they're optional mod soldering points

[blind_ripper]

largon are u sure that the mod will work ?

[blind_ripper]

use a 100k vr from the lower red point to ground and u got ure self a gpu mod tested and its good

[Heinzkopf]

Hi
the result was around 1840-1850 Ohms from both of these Points to Ground.

So i have to find a ~37kOhm VR and solder it between one of these red points and ground- Is this correct?
Lowering the resistance will have the effect of rising vGPU?

Hmm is this safe? i don't wanna destroy my new card
Maybe some other people can confirm this mod?

Another big problem is the soldering act- These Points are damn small and i need a very fine SMD soldering iron i think :/

[Heinzkopf]

use a 100k vr from the lower red point to ground and u got ure self a gpu mod tested and its good

Hmm ok.. 100k seems more safe?!
How did u solder it? i Mean what for a soldering iron do u use

[largon]

Heinzkopf,
Based on your measurement a VR rated 50k would be the optimal choice. 100k works too but it will be a little rougher to tune compared 50k. Solder it from either of the red points to ground and you're done.

[blind_ripper]

the 100k set to 67k ohms gave me a start voltage off 1.088vgpu idle so with 50j omhs that will be 1.15vgpu .
greetz blind

[Heinzkopf]

okay,
thank you both.
currently i have 1.1Vgpu load with bios, i will use 50k ohms from lower red dot to ground to start with 1.15vgpu load then

But first i have to look after a thin soldering iron

[blind_ripper]

now can someone find the vmem mod on this little pup ?

[Heinzkopf]

Yes that was cool, too.

Beside this another question- how much voltage would u declare safe for 24/7 usage? i mean i have a good heatsink, but i'm not sure..

[Rol-Co]

now can someone find the vmem mod on this little pup ?

Whats on this chip
http://img142.imageshack.us/img142/3900/back2ma6.th.jpg

[Heinzkopf]

@Rol-Co
Which chip do u mean exactly?

@largon and blind_ripper
it works perfectly with 50kOhm resistance for me.
I start off with ~1.135v IDLE and 1.105v LOAD

btw is it allowed to change the VR while computer is running or do u have to switch off every time u change the resistor?

[largon]

Always tune the VR while computer is powered on and continuosly measure the voltage you're tuning.

[micheskillz]

Yeah, where to do the vmem mod? It seems that there is Hynix memory chips on these cards, atleast it says so on the chips

I got the same card. Thought it was nvidia reference so i got myself a 500 ohm VR before i knew it, and now i found this thread.

Thou my card doesn't have the exakt same Phase controller. Mine is named L6713A too, but
990B2 VH
MYS 99 751

instead of
990TS VH
MYS 99 729
as the one in topic has.

My sparkle 8800GT 512MB is revision S1.2

My measurements on those red dots are 1634 Ohms on both of them.
What kind of VR do i need? 1634 * 20 = 32680. So, will a 50k VR be fine for me too?