8800GT voltage mods

[edo]

Would be easier if you took a picture of your card on the area you think something is missing. Anyways, there are tons of unused SMD solder pads on the backside...

i have no digit cam right now i'll be gratefull to anyone can help me posting an high res photo of the back of the card in oppite site of gpu ( pcb right back gpu) thank youuu

[scottc19]

So the "repaired 8800gt" failed the other day, when I was gone. When I got back computer was on, but no monitor signal. I'm pretty sure the electrical tape moved and one of the connections broke... but I can't be completly certain. Anyway I carefully redid every connection and just used a 15ohm resistor instead of the vr resistor(this way wires aren't all over the board and there isnt any tape). So now everything is like before, except it crashes shortly after it boots up... I put it in, and turn it on. It posts at 1.03v, then goes to my next screen which happens to be vista's dos error recovery menu. I let it stay here for maybe a minute, then screen starts going crazy, vertical moving of items, then crash. When it crashes Voltage reads 0 and monitor no longer has a signal. I'm pretty sure to get it to boot again I have to take it out and put it back in.

My guess is that the voltage is too low and the core is crashing, or some low current protection is kicking in. I think this can be fixed, by doing the voltage mod. My other guess is that the card is broken-but we will assume that this is not the case

Anyone have any ideas, before I do the voltage mod, just thought I would ask and get some input / make sure I didn't overlook anything.

Thanks

[scottc19]

I did the volt mod, but still no go... It seems to be worse now, regardless of the voltage... for the most part. Now about a second after I turn it on, the volts go to zero. All of my soldering connections seem fine, although some are very difficult to check. Mostly just the ones to the two points marked "ok" in my last picture. I know that at least one of the "ok" points has a good connection, but its difficult to know if they both do. I'm just about out of ideas on what could be wrong now...

[scottc19]

Alright time for follow up, it seems that I just had a bad connection to the points marked with ok... now it boots up find and I am in windows with no crashing. 1.1v idle in windows now. My rma'd 8800gt gets here today, maybe be next week or the week after ill put some scores up with both in sli, volt modded, w/water and when I get a q6600...

[Nosfer@tu]

Im not sure how to reconise the OVP mod kicking in?

If it kicks in the Vgpu should be 0 or 0.2-0.3

If the chip crashed because of to high OC it should keep the 1.35 VGPU ?

[largon]

OVP causes a trip without any load just as soon as a certain voltage level is achieved. OCP would cause tripping at load. Both result in 0.X vGPU.
Crashing due to a too high OC shouldn't cause any change in vGPU.

[largon]

edo,
http://img215.imageshack.us/img215/7...desmdsckc9.jpg
(2876x1920, 1.4MB, JPG)

[edo]

edo,
http://img215.imageshack.us/img215/7...desmdsckc9.jpg
(2876x1920, 1.4MB, JPG)

really thank Largon , you are great!! the best pic oh hardware i have ever seen!! I checked the board and is perfect!

I'm stable at 756/1944/2000 in all games but colin dirt that makes me to be stable @ 756/1890/2000 ..all with 1.1 volt by bios..

is there a way to overvolt more by bios?

thank you again!!

[jason4207]

Good work!

I thought she was a goner.

Do you have any pics?

[scottc19]

Thanks, I will try and borrow my gf's camera and post some.

[nvrmind]

My GPU volt mod:

MSI 8800GT

Max Clocks @ Default vcore w/ 1.1v bios mod was 710/1775/1000

Currently running 760/1900/1000 @ 1.2v without artifacts in ATI Tool

Aiming for 800 core

[largon]

nvrmind,
I think I hear your card scream:
"Need ... more ... v o l t a g e!"

btw,
Funky red PCB - it makes it look like a Radeon.
:P

[natedog420]

yes more voltage hehe. im runnin my gt whats in my sig with no flaws and nothin over 60c at the very most. with a crap block and crap rad in my loop. you have a nice setup there looks nice.

edit: largon did you have any high pitch sound from your card at all. when im heavy loaded it makes a high pitch sound not to noticeable but its there. i dont care cuz i like to hang on the edge just wondering if you heard the same before. only runnin 1.42v loaded give or take +/- .01. nothin to high but 840 core and 2000 shader is nice!

[largon]

natedog420,
I got the buzzing too, it's quite common in 8800-serie cards it seems.
btw, I would advise against removing the resistors as this will completely prevent the phase controller from maintaining balance between the two phases = not good, at all. This type of OCP mod may be dangerous...
The safe(r) way is to do it like described in G80GTS OCP -thread:

[quake6]

natedog420,
I got the buzzing too, it's quite common in 8800-serie cards it seems.
btw, I would advise against removing the resistors as this will completely prevent the phase controller from maintaining balance between the two phases = not good, at all. This type of OCP mod may be dangerous...
The safe(r) way is to do it like described in G80GTS OCP -thread:

I was wondering can I use 1.2k fixed resistor something like this?

http://www.queenmao.com.tw/image_pro...007-Carbon.jpg

[largon]

I solder a 500kOhm Resistor to the left Alternativ Point (I was much easyer than the Point in the Middle.

The Mods Works good ... so long...
I can tune up and down the Voltage
and I can raise the Clock BUT
If I get more than 1,3 V the Card freezes i everey Benchmark.
(...)

500kohm? Is that a typing error?
The VR one is supposed to be 500ohm, not 500kohm (kilo-ohm).

Is it possible that the Mod works better on the middle Soldering Point?

All marked mod soldering points are equal.

I was wondering can I use 1.2k fixed resistor something like this?

http://www.queenmao.com.tw/image_pro...007-Carbon.jpg

Yes.

[Kabauterman]

500kohm? Is that a typing error?
The VR one is supposed to be 500ohm, not 500kohm (kilo-ohm). All marked mod soldering points are equal.
Yes.

Ohh ^^ yes I mean 500 ohm ...

I think I have find the Problem

I must do the OCP mod :-(

[EightyDuce]

Ohh ^^ yes I mean 500 ohm ...

I think I have find the Problem

I must do the OCP mod :-(

Yeah thats the OCP kicking in, drop some 3.92k in parallel on the caps next to the X78s and you'll be set. There should be some pictures to help you in this thread.

[jason4207]

Largon, 1.2k seems kind of low from what I've seen/read. Viper John recommended 3.8-4.2k to me for ~25% OCP headroom above stock. Lower R values gives more headroom.

My understanding is that the lower the R value the harder it is for the phase controller to balance the load b/n the phases, so you don't want to go too low.

Your thoughts?

[babalouj]

Ok guys, is it possible for someone to post pictures and explanations of the OVP mod, OCP mod, and the Vmem (buck) mod? People keep refering to other posts and the pictures may be there and explanations in other places so its hard to keep track. I have done the OVP and Vgpu mod but for the OVP mod I removed resistors and I would like put them back and do it with fixed value resistors this time. Also, what is the correct value to put in parallel across the capacitors for the OCP?

[jason4207]

No need for OVP mod.

OCP mod (solder (2) 603 SMR's in parallel w/ the (2) SMC's around the Primarion chip):


I used 3.92k SMR's, but 3.8-4.2k should be fine.



vmem buck mod (50k VR to points shown...this lowers vmem):

[largon]

jason4207,
Adding 1.2kΩ resistors would weaken OCP by 50%, 3.8-4.2kΩ is just playing safe... :p

babalouj,
A comprehensive guide to G92GT/S vmodding will be available soon.

[babalouj]

Jason4207, Can you please repost the pictures, the thumbs arent clickable.

Largon, sounds good, how soon are we talkin?

I have a stable overclock of 850/2150/2000 @1.32V loaded anymore voltage or overclock and I get a screen completely filled with pink C's randomly while gaming then BSOD after like 3-5 seconds. I am assuming thats OCP kicking in? Fuzzy cube and 3dmark06 are stable and temps are low 50s.

[largon]

When OCP is triggered, GPU power regulation will be completely shutdown meaning all you see is a sudden freeze followed by a black screen.

Availability of the all-round guide is a matter of few days.

[babalouj]

Ah, so pink C's is more likely a memory issue. What voltage are people having the most success with on qimonda memory? I have seen most people around 1.9V but I would like to get more inputs.