8800GT voltage mods

[largon]

This guide applies only to G92 based nVIDIA 8800GS, GT, GTS and 9600GSO reference boards. If your card has different layout feel free to report here, and, if possible post clear pictures of the card.


http://www.xtremesystems.org/forums/...1&d=1196804211
Higher resolution image @ Imageshack:

Addendum:
- stock vGPU voltages for this card are 1.05v (2D idle) and 1.15v (3D load)
- stock vMEM voltage for Qimonda GDDR3 (HYB18H512321BF-10) is 2.0v ±5%
- vMEM mod has been deemed almost useless as Qimonda GDDR3 does not OC any better at higher voltages
- 1kΩ variable resistor can be used for the vGPU mod in order to maintain minimum voltage close to stock. 500Ω VR will be more accurate to tune but it will also force vGPU slightly higher than stock even when the VR is tuned for lowest vGPU = maximum resistance.
- vGPU pencil mod turned out to be virtually impossible
- usage of a multimeter is required for tracking the vGPU
- ENJOY!

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Complete GeForce 8800 GS/GT/GTS Voltmods for reference PCB @ techPowerUp!

[metro.cl]

will help when i get home, i'm looking for a vmod becuase that is the limiting factor on my overclock

[largon]

Btw, here are some easily accessible vGPU measuring points:

[HousERaT]

Pencil mod anyone if it's possible?

[kiwi]

Pencil mod anyone if it's possible?

Only vmem

[nordicpc]

I can't wait to see this fall out. I'll have one on Thursday, and am anxious to void some warranties with a VF-900.

[largon]

Yup, vMEM is definitely pencil modable and actually, vGPU should be too if you're careful [EDIT: VGPU PENCIL MOD UNTESTED! DO NOT APPLY!]). BUT a multimeter is a MUST for a safe vGPU pencil mod... The resistor is awfully tiny but it is doable, it's possible because the affected resistor has higher resistance than on G80GTS/GTX thus pencilling is easier.

The modable resistor for vGPU is the one marked with numbers 2 and 4, but I need measuments of the requested points to be able to calculate the target values for VRs / pencil resistance.
EDIT: VGPU PENCIL MOD UNTESTED! DO NOT APPLY!

For vMEM I need the measurements for spot7-to-spot8/ground in the second pic.

Would someone bother measuring the stock vGPU?
Measuring points can be found in post#3.

[dinos22]

Yup, vMEM is definitely pencil modable and actually, vGPU should be too if you're careful. BUT a multimeter is a MUST for a safe vGPU pencil mod... The resistor is awfully tiny but it is doable, it's possible because the affected resistor has higher resistance than on G80GTS/GTX thus pencilling is easier.

The modable resistor for vGPU is the one marked with numbers 2 and 4, but I need measuments of the requested points to be able to calculate the target values for VRs / pencil resistance.

hmmm might be worth looking into

what sort of resistance should we be looking at for "safe initial test"???

[largon]

dinos22,
The problem with pencil vGPU mod is the low resistance between vsense and ground. Pencil vGPU modding was quite difficult on G80GTS/GTX eventhough their vsense_pin-2-ground resistance was 35Ω and since G92GT's vsense reads even lower (15Ω) pencilling becomes one step more difficult. 15Ω is awfully low to be penciled; it leaves very little room for error. Vsense-2-ground resistance could easily dip way too low consequently yielding a dangerously high vGPU.

But ofcourse, there's nothing that really prevents from experimentally pencilling the little bugger and measuring the resultant resistance, no harm done there. Just remember to apply pencil very slightly, and do not power up the card blindly without being sure the resistance doesn't get too low. And since I don't have the card I can't tell how low a resistance yields what vGPU. Hence, I have no idea what are safe resistances. We need someone who has done the VR mod to provide resistance readings...
People who have done the mod with VR: How low Ω between the vGPU mod solder points @ 1.2V / 1.3V / 1.XV?)

!CAUTION, UNTESTED MOD! READ THE ABOVE TEXT BEFORE MODDING!
Here's the pencillable resistor (optionally, you can pencil the one next to it on the right side):
!CAUTION, UNTESTED MOD!

!CAUTION, UNTESTED MOD!

[dinos22]

i think pencil modding *looks* to be a bad idea and maybe some extra loud warnings are necessary in posts referring to it i think

[HousERaT]

/subscribed

[metro.cl]

Between 7 & 8 is 612
Between 2 and 4 is 011
Between 2 and ground is 015

1 to 2 = 002
1 to 3 = 002
7 to ground = 002

vGPU 1.06v

[dinos22]

here are all the other photos i posted there




here is an actual image of my card here

Thanks, dinos22.
Need clarification on the existence of certain traces and few resistance measurements, see attachements.

First pic:
There should be traces between points 1, 2 and 3. It certainly does look like there is a trace between 2 and 3, but is there one between 1 and 2? = if there are traces between 1, 2 and 3 then resistance between each is ~4-6Ω.
Also,
Resistance between points 2 and 4? (might be <10Ω)

Second pic:
Resistance between points 5 and 6? (might be around 500Ω)

if i set 200 on dial i get 10.4 on points 2 & 4
if i set 20K on dial i get 1.10 on points 5 & 6

looks like my battery might be going on the DMM

best view i can get with camera
naked eye won't work just can't see that

[dinos22]

if i set 200 on dial i get 10.4 on points 2 & 4
if i set 20K on dial i get 1.10 on points 5 & 6

so how do you read this as actual values
can someone tell me

would it be 10.4*200=2080Ω or 2.08kΩ
1.10*20K=22000Ω or 22kΩ

[metro.cl]

point 5 & 6? i get similar reading with you Dino just a couple of 0X of diference

[largon]

Thanks metro.cl and dinos22!

Between 2 and 4 is 011
Between 2 and ground is 015

I'm suprised to hear these points measure that low values. Gonna have to have another look at the vGPU resistor network...
Everything else is like I expected. Especially the vGPU... Lot's of headroom to crank it up, the chip should take 1.4V with ease. :P

point 5 & 6? i get similar reading with you Dino just a couple of 0X of diference

Points 5 & 6 were discarded because that particular resistor wasn't in the end that very interesting.

so how do you read this as actual values
can someone tell me

would it be 10.4*200=2080Ω or 2.08kΩ
1.10*20K=22000Ω or 22kΩ

10.4 @ 200 dial = 10.4Ω
1.10 @ 20K dial = 1.10kΩ = 1100Ω
The dial selects the maximum measureable resistance. If the result is higher than the selected dial option then the device will simply display "1". So, in a way, one has to know approximately how much the measurement's result should be in order to accurately measure resistance.




Oh, and here is the vMEM mod & vMEM measuring points (stock vMEM is 1.8v &#177;5&#37:

[metro.cl]

Thanks metro.cl!
I'm suprised to hear these points measure that low values. Gonna have to have another look at the vGPU resistor network...
Everything else is like I expected. Especially the vGPU... Lot's of headroom to crank it up, the chip should take 1.4V with ease. :P10.4 @ 200 dial = 10.4Ω
1.10 @ 20K dial = 1.10kΩ = 1100Ω
The dial selects the maximum measureable resistance. If the result is higher than the selected dial option then the device will simply display "1". So, in a way, one has to know approximately how much the measurement's result should be in order to accurately measure resistance.




Oh, and here is the vMEM mod & vMEM measuring points (stock vMEM is 1.8v ±5%):

any way to pencil mod it? i dont have VR here

[dinos22]

interesting. 10.4 @ 200 dial = 10.4Ω
1.10 @ 20K dial = 1.10kΩ = 1100Ω
The dial selects the maximum measureable resistance. If the result is higher than the selected dial option then the device will simply display "1". So, in a way, one has to know approximately how much the measurement's result should be in order to accurately measure resistance.

i get it now thanks buddy

[jason4207]

Golden Tiger - I followed you over here from OCForums, so I know all about it!

So it sounds like setting the 500VR to max is the best starting point. See how high I can OC at that vGPU, and then raise a little bit at a time. Once I start getting to the point where extra voltage doesn't seem to help more or temps get too high, stop. Is there a voltage I should definitely stop at no matter what?

I know these are new chips, but are there generally accepted guidelines like:
up to 1.2v is safe
1.2-1.4v should be OK
1.4+v is dangerous?

I said 1.4v earlier b/c of this post:

Everything else is like I expected. Especially the vGPU... Lot's of headroom to crank it up, the chip should take 1.4V with ease.

[GoldenTiger]

Golden Tiger - I followed you over here from OCForums, so I know all about it!

I said 1.4v earlier b/c of this post:

Sorry if I sounded rough with my post, it was not meant to be rude . The general guideline you just outlined yourself should be right, though.

[jason4207]

Sorry if I sounded rough with my post, it was not meant to be rude . The general guideline you just outlined yourself should be right, though.

You were fine (no roughness detected). I just found it funny the way you responded w/ your explanation of which HR03 to get. I was the main guy telling everyone over at OCForums that there are different versions of the HR03, and just b/c one review said "the HR03 doesn't fit" it was b/c they used the one designed for the GTS/GTX (HR03+), not the one designed for the 6/7 series (HR03-Rev.A). Rev.A "should" fit, but I may wait a bit and see if TR releases a specific version for the GT, to make sure I get the right sinks for the RAM and Vregs. Or I'll just buy a bunch of small sinks and make it work!

I should be good on slots. I plan on staying single-card. I have the P5K-Premium. Only PCI device is my Auzentech Xplosion sound card...I might get a HD Tuner card at some point, though.

Also your pic, which I've seen posted several times over there, made me laugh just b/c I've seen it so many times.

I can't wait to see your results! I may let you be my guinea pig if you don't mind.

[GoldenTiger]

I just found it funny the way you responded w/ your explanation of which HR03 to get. I was the main guy telling everyone over at OCForums that there are different versions of the HR03Also your pic, which I've seen posted several times over there, made me laugh just b/c I've seen it so many times.

I can't wait to see your results! I may let you be my guinea pig if you don't mind.

Ahhhhhhh LOL, I didn't realize you were the same person . Yeah, that is pretty funny then .

I'll guinea pig... , but only if I can get the 1k ohm one locally and have it work I think, the cost because of minimum order + shipping is too high online at the place I found with 500 ohm VR's . Anyone know if the 1k ohm will work (i.e. could I just turn it to 500 ohms with the knob and it would work)?

[largon]

metro.cl,
Sure, just apply a little pencil over the resistor and measure the resulting resistance & vMEM after every application. I don't know how well Qimonda GDDR3 responds to voltage, so, just to be safe make sure you keep the resistance over 530Ω. This way the vMEM doesn't go above 2.0V

[largon]

How about the resistance between these 2 points?
Still about 11Ω?

edit:
It's 00:23 AM over here... And I'm recovering from a nasty flu.
I'm gonna hit the bed.
&#166;o

[wittekakker]

VGPU in BIOS is set to 1,05V. I saw 1,1V is the highest possible value, maybe it works and boosts your overclock 2%

Made modbios via Nibitor, here is the zipfile, use at own risk.