8800GT voltage mods

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11-13-2007, 08:38 PM
JKDC

Quote:

Originally Posted by Mysterfix

I have no idea. I measured the OVP resistor and got 3.22k So I penciled it down to 2.77k and it seems to have done the trick!

I'm now able to set vGPU to 1.35v which is 1.4v under load! I played a 1/2hr. of CoD4 without any issues. I used to get a black screen after less than a minute.:D

It would be nice if one of the experts could tell me what the proper resistance should be for the OVP mod on GT cards.:rolleyes:

Can you pinpoint which resistor it is and I can check mine. I am at 810/1944/2000 with air cooling @ 1.285 volts under load (Thermalright V2). Only 63C under heaviest load. I would like to try the pencil mod for the OVP to see if I can catch you water cooling boys. LOL
11-13-2007, 09:55 PM
Mysterfix

http://www.xtremesystems.org/forums/...5&postcount=65
11-14-2007, 02:09 AM
trans am

1 Attachment(s)

here's the image of my completed vmod.
11-14-2007, 04:52 AM
Daveb2012

Quote:

Originally Posted by trans am

here's the image of my completed vmod.

nice how is OCing
11-14-2007, 07:32 AM
trans am

Quote:

Originally Posted by metro.cl

If you soldered you need to lower the resistance to get more volts, turn a little and check vGPU with a tester, and then try OC.

only bios so far

so turn clockwise or counterclockwise? also should I change multimeter from ohms setting to voltage now? is the best place to measure the vgpu on the solder points I made? because thats would be the easiest place to put the little crab hooks. otherwise i'm going to solder to little wires to the vgpu measure points and clamp on these. thanks in advance
11-14-2007, 08:13 AM
Renegade5399

Quote:

Originally Posted by Mysterfix

http://www.xtremesystems.org/forums/...5&postcount=65

Thank you sir!
11-14-2007, 08:43 AM
largon

Quote:

Originally Posted by trans am

so turn clockwise or counterclockwise?

Basically it doesn't matter as turning the VR the wrong way does absolutely nothing. You need to tune down the resistance (from ~14.5Ω) between the solder points in order to increase vGPU. Easiest way would be to measure the resistance and make sure it's around 15Ω, then power on the system and tune the VR until satisfactory vGPU is reached.

Quote:

also should I change multimeter from ohms setting to voltage now?

Yup.
That's if you're going to measure vGPU. :)

Quote:

is the best place to measure the vgpu on the solder points I made?

No, the solder points have nothing to do with vGPU voltage - except ofcourse via the mechanism the mod works.
vGPU measuring points are the violet points in this pic.

btw, this your 1st vmod?
:D
11-14-2007, 08:51 AM
trans am

Quote:

Originally Posted by largon

Basically it doesn't matter as turning the VR the wrong way does absolutely nothing. You need to tune down the resistance (from ~14.5Ω) between the solder points in order to increase vGPU. Easiest way would be to measure the resistance and make sure it's around 15Ω, then power on the system and tune the VR until satisfactory vGPU is reached. Yup.
That's if you're going to measure vGPU. :) No, the solder points have nothing to do with vGPU voltage - except ofcourse via the mechanism the mod works.
vGPU measuring points are the violet points in this pic.

btw, this your 1st vmod?
:D

THanks for all the info. I appreciate it. Yes, my 1st mod. how did I do? I guesss we wont know until I turn it on.
ps. my best clocks before the mod with a mcw60 is here:
http://i239.photobucket.com/albums/f...alsmith/37.jpg
http://www.xtremesystems.org/forums/...1&d=1194763028
11-14-2007, 11:01 AM
central

Did the ovp mod on my 8800gt.
It still kicks in at 1,3V.

I use a 100k vr and set the resistance to 5k ohms after soldering.
Without the mod the resistance was 5,23k.

Should i try to decrease the resistance?
11-14-2007, 12:06 PM
Renegade5399

Bring it down to around 2.7k.
11-14-2007, 06:13 PM
Renegade5399

Got my 1k and 50k pots today. I am lucky enough to have a local electronics supply.
11-15-2007, 12:05 AM
trez0r

Imho you need to increase the resistance of OVP resistor to make it allow for higher voltages. Correct me if im wrong. At least it was that way on my giga 7900gs.
11-15-2007, 12:48 AM
coolice

hey guys,wat core speed u guys get after vmod?need some rough idea about it while waiting for my 88gt:D
sory..i don keep track on this thread always:p:
11-15-2007, 01:27 AM
largon

trez0r,
Well, what can I say, this isn't a 7900GS...
:)
11-15-2007, 08:20 AM
cowie

on topic of ovp.
i thuoght that you decrease resistance to said ovp resister and that inturn raises resistance of core volts?
which you just compensate by turning down resistance on v-mod til you reach desired volts?
have tryed it works but not nessaciry for me on air.
11-15-2007, 09:02 AM
winbond

personally i don't like pencil mods, it's convenient but not reliable,

would it be possible to just disable the OVP circuit entirely instead of modding it to kick in at higher voltage?
11-15-2007, 12:23 PM
Pacha

Quote:

Originally Posted by winbond

personally i don't like pencil mods, it's convenient but not reliable,

would it be possible to just disable the OVP circuit entirely instead of modding it to kick in at higher voltage?

Same opinion here, I guess soldering the proper VR will make OVP higher and so you'll be able to put more vgpu before the card goes OVP

anyway, I'd prefer not to bother with solder just for OVP mod, this is boring, if the pencil mod works well on it at a particular resistance value, a simple piece of adhesive tape to secure it will be ok
11-15-2007, 01:20 PM
JKDC

At what specific voltage does the OVP kick in? I measured my volts at 1.305 running ATItool so it must be a bit higher than 1.3. I am using a Fluke dmm so it should be pretty accurate.

Can anyone else confirm the pencil mod works? My mosfet sinks should be here tomorrow and I will be ready to try it then.
11-15-2007, 01:46 PM
m@d-m@x

Quote:

Originally Posted by Renegade5399

Guys, listen up. Running the memory at 2000 or higher for long period of time can be an issue.

See here:

http://www.hardforum.com/showpost.ph...8&postcount=13
And here:

http://i4memory.com/showthread.php?t=5030

Sorry if linking across forums is taboo, but it's important. You can slowly kill the memory running it over 2k.

EDIT: I have been debating on an 8800GT or the new ATI offering. Since my volt modded 7900GT was so good to me I think I will go with the 8800GT as well. Just wanted to get this post up for you guys.

After reading the hardforum link im a bit confused after this post http://www.hardforum.com/showpost.ph...95&postcount=1 Does that mean when i in Ntune or Rivatuner crank the RAM up to 1000MHz from standard 900, it actually runs at the dangerous 2000MHz?
11-15-2007, 01:54 PM
largon

Yes.
"2000MHz" is actually just 1000MHz but since we're talking about dual data rate memory it's effectively 2000MHz (= DDR-2000) - which according to a "certain BFG technician" is bad for Qimonda GDDR3.
11-15-2007, 01:57 PM
Renegade5399

Oh my I need to find my magnifier. I forget how small of an area I'm dealing with.
11-15-2007, 03:23 PM
Mysterfix

Quote:

Originally Posted by JKDC

At what specific voltage does the OVP kick in? I measured my volts at 1.305 running ATItool so it must be a bit higher than 1.3. I am using a Fluke dmm so it should be pretty accurate.

Can anyone else confirm the pencil mod works? My mosfet sinks should be here tomorrow and I will be ready to try it then.

It's actually more like 1.35v under load as the gpu draws more power when in use. So setting 1.3v at idle results in about .05v -.06v increase under load.

On another note: The OVP mod doesn't work, I had my card black screen on me last night after about an hour of Crysis.:shakes:
11-15-2007, 03:44 PM
JKDC

Quote:

Originally Posted by Mysterfix

It's actually more like 1.35v under load as the gpu draws more power when in use. So setting 1.3v at idle results in about .05v -.06v increase under load.

On another note: The OVP mod doesn't work, I had my card black screen on me last night after about an hour of Crysis.:shakes:

Did you pencil it down as far as it would go? Why would it go for a solid hour? It seems like it would go black immediately. Maybe if you lower the voltage a bit (.01) it would make it.

Oh well...1.35 should be enough on air I guess. Hopefully I can go to 1.34 without problems. I think I'll try it now. :D
11-15-2007, 03:50 PM
96redformula

Anybody want to put it in step by step terms for the Vmodd. I had done the 7900GT Vmodd in the past with a silver ink conductive pen and it worked great. Can you all put it in laments terms on what to buy and how to do it? I have both the gel superglue and the silver ink pen, so I can probably do that without taking a big chance on saudering.

I was going to wait for the 8800GTS G92, but if I can get a vmod on a 8800GT I will take that route.

Cooling: MCW60, Swiftech Ramsinks, Swiftech VReg sinks
11-15-2007, 04:34 PM
Mysterfix

Quote:

Originally Posted by JKDC

Did you pencil it down as far as it would go? Why would it go for a solid hour? It seems like it would go black immediately. Maybe if you lower the voltage a bit (.01) it would make it.

Oh well...1.35 should be enough on air I guess. Hopefully I can go to 1.34 without problems. I think I'll try it now. :D

I don't know why it's not holding but I don't want to go any lower without finding out what is safe.

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