8800GT voltage mods

[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!!

[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...

[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!

[scottc19]

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!

-Yes, this is a common occurence at least as far as I know

Keep tweaking I bet you could push the shader further.
Also at 1.42 you are probably venturing into the ocp realm. Did you do the ocp mod?

[natedog420]

ya did the 2 resistor removal mod awhile ago. got sick of it hit ocp so i did it. ive been as far as 870/2050/1970 but at 1.47 volts it gets a lil scary to me. i would like to own the card for awhile so i backed it down a lil bit.

[scottc19]

ya did the 2 resistor removal mod awhile ago. got sick of it hit ocp so i did it. ive been as far as 870/2050/1970 but at 1.47 volts it gets a lil scary to me. i would like to own the card for awhile so i backed it down a lil bit.

Did you unlink the shaders and core? / just curious at 1.50 my shaders were up to 2300.

[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:

[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.

[jason4207]

Pics fixed above. Largon, feel free to use them in your guide if needed.

On the GT 1.84v vmem was the best for me on one card, and 1.8v was better on another. The GTS seems to like a bit more voltage (1.96v). You'll just have to play w/ it. See my quote below for my comments on tuning for the 'sweetspot'.

Both my GT and GTS have Qimonda RAM chips. I wish I had some Samsung's! The way I understand it is that both the vRAM, and the memory controller are fed from the same voltage line. The vRAM by itself should respond better to more voltage, and I think the specs have them listed up to 2.5v. The problem arises b/c the memory controller doesn't respond well to voltage. So, if you start raising the voltage you are just making the controller crash, and that is seen as the memory avalanche.

There is a definite 'sweet spot' that I was able to find on both cards. The GT liked ~1.84v, and the GTS liked ~1.96v iirc. Dialing in that sweet spot actually had me making the smallest turns possible on the VR to find that spot b/n memory avalanche (red or green crap all over the screen) w/ lock-up if the voltage was too high, and just plain lock-up if the voltage was too low. Those last few changes I made to the VR in finding the sweet spot didn't even register on my DMM, but they did allow me to pass 8 loops of 'Battle of Proxycon' form 3DMark03 at 1 higher notch on the slider. On my GTS I started at 1062 stock to 1101 w/ the mod. That was pretty easy, but it was tedious work to get 1107. On my GT I was able to go from 1026 stock to 1056 w/ the mod, but had to go back down to 1044 after I increased the core/shader clocks and voltage.

I forgot to mention this above, but a big thanks goes out to Viper John for all his highly informative help he gave me via email. And also to all you guys here like Largon who helped to find these mods. I'm not sure who all found what, but kudos to you gentlemen. My knowledge has increased 10 fold in the past couple months as I've researched, prepared, and then accomplished these mods.

Thank you!

Edit: I think AquaMark3 is a good test for OCP. Right at the end before it gives you the score the current spikes, and you'll see OCP shutdown if you have the vGPU too high.

[adpr_02]

Hey, maybe you guys can help out a bit. I have a freakishly good 8800gt. It runs STOCK at 800/1900/1010. So I decided to Vmod it, maybe i can make it even better. I attatched the resistor as per the instructions ont he first page of this forum, put 1.3v through it (vf900 cooling) and can push it up to 900/2100/1000.

This is all good, but I get MASSIVE artifacts after a while. So I put my overclock back a bit, and still artefacts. I then run my old overclock, and STILL get artifacts - when before I would get none. THing is, I get them after a while, which leads me to believe that a part of my card is overheating or something (other than core/memory).

It did this before my vmod, so I put heatsynks on the moffsets, and pretty much every other big black part on my card and slapped another fan on those and it worked. Obviously, it doesn't do anything now.

Anybody got any ideas?

[babalouj]

Jason and Largon, I removed the 78X(63.4ohms) resistors from my card (while mimicing a mod from earlier in the thread) and am trying to put them back. I have some 77X (61.9ohms) and some 79X(64.9ohms) resistors, would you go higher resistance or lower resistance for those? The 78X seem to be part of the same circuit as the capacitors used in the isen1 and isen2 circuits. My initial guess would be that 2ohms (2&#37 wont make a difference but I would just like some input first. If I had the darn datasheet for the px3544 i would be able to answer my own question...

[nvrmind]

Has anyone had trouble overclocking their memory to previous stable levels after the gpu volt mod? My memory could do 1000 before, now I'm having trouble with it @ 975. I think maybe my core hates 800mhz even if I pump the voltage beyong 1.3v. It seems stable if the memory is left at 950 though. I have Hynix chips (HY5RS123235B) which are rated to do 1000. Stock memory voltage is 2.00v. Any thoughts?

Also, what are the symptoms of OVP kicking in?