7800GTX overclocks with Volt Mods??

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08-18-2005, 01:06 PM
maverik-sg1

Quote:

Originally Posted by ViperJohn

Yu got a URL on those so I can look at them???

Viper

Model number: 3266W-1-201 BOURNS

CERMET POTENTIOMETER ROHS COMPLIANT:NO; SERIES:3266; RESISTANCE MAX.:200OHM; RESISTANCE MIN.:2OHM; RESISTANCE TOLERANCE:+/- 10 %; NUMBER OF TURNS:12; POWER RATING:0.25W; PACKAGING:BULK; TERMINAL TYPE:PCB; ADJUSTMENT TYPE:TRIMMER; RESISTANCE:200OHM

Found here:

http://www.newark.com/NewarkWebComme...ction&x=12&y=7

Shigs is gonna do the vmods for me and these are the units we selected here in the UK.

Check it out and post your thoughts on yes/no here.

Many thanks in advance Viper John

Also: When making the mods - does it matter what BIOS is installed? For example if the 'no temp monitoring' BIOS was installed would this have any effect of the mod itself?

Cheers again

Mav
08-18-2005, 01:08 PM
happyhero

Quote:

Originally Posted by ViperJohn

Yu got a URL on those so I can look at them???

Viper

I am using a 200r resister for my 7800GTX.
i can only turn it 1 ful revolution so i have to be carefull when i am upping the voltage.
08-18-2005, 01:19 PM
ViperJohn

Quote:

Originally Posted by maverik-sg1

Model number: 3266W-1-201 BOURNS

CERMET POTENTIOMETER ROHS COMPLIANT:NO; SERIES:3266; RESISTANCE MAX.:200OHM; RESISTANCE MIN.:2OHM; RESISTANCE TOLERANCE:+/- 10 %; NUMBER OF TURNS:12; POWER RATING:0.25W; PACKAGING:BULK; TERMINAL TYPE:PCB; ADJUSTMENT TYPE:TRIMMER; RESISTANCE:200OHM

Found here:

http://www.newark.com/NewarkWebComme...ction&x=12&y=7

Shigs is gonna do the vmods for me and these are the units we selected here in the UK.

Check it out and post your thoughts on yes/no here.

Many thanks in advance Viper John

Also: When making the mods - does it matter what BIOS is installed? For example if the 'no temp monitoring' BIOS was installed would this have any effect of the mod itself?

Cheers again

Mav

This is a better choice:

http://www.newark.com/NewarkWebComme...KU=03F3876&N=0

Viper
08-19-2005, 03:52 AM
maverik-sg1

Hi Viper John - the only difference I can see is the power rating from 0.25w to 0.5w, I dont think we can get hold of the 0.5w unit in the UK - if we use a 0.25w unit and it blows - is it safe to ssume that the unit will just refer back to default voltages?

Cheers

MAv
08-19-2005, 05:39 AM
K404

For the (few) volt-mods I`ve done, I`ve taken it that no real power is dissipated through the resistor/potentiometer, so rating doesnt matter?

Please dont take that as hard truth, I`ve never checked..

Kenny :)
08-19-2005, 05:50 AM
persivore

The variable resistors that ViperJohn pointed out have 25 turns instead of 12, so the voltage adjustment with them will be finer ;)
08-19-2005, 07:09 AM
maverik-sg1

mmmmm I am just looking to set it at 1.5v-1.65v, the goal is to get 615Mhz core clock on water - so dont think I need a fine adjustment - although with teh benfit of now knowing this - I would go for the 25 turn in future.

Thanks for the information guys - just waiting for confirmation from the Viper man to see if 0.25w is okay?

Cheers

Mav
08-19-2005, 09:55 AM
ViperJohn

Quote:

Originally Posted by maverik-sg1

Hi Viper John - the only difference I can see is the power rating from 0.25w to 0.5w, I dont think we can get hold of the 0.5w unit in the UK - if we use a 0.25w unit and it blows - is it safe to ssume that the unit will just refer back to default voltages?

Cheers

MAv

The power rating of the trimmer is of no consequence. The difference is the 3296 is a 25 turn unit and the style allows the trimmer to be attached right at the mod site with double sided foam tape with the trim pot legs going to the solder points without adding noise inducing lead wires.

Viper
08-19-2005, 01:46 PM
maverik-sg1

I see thanks for the input Viper J - You da man!!
08-19-2005, 02:17 PM
ViperJohn

Quote:

Originally Posted by maverik-sg1

I see thanks for the input Viper J - You da man!!

Also I would limit your Vcore to 1.60 at least for now. The G70's tolerance to increased Vcore is not well known yet. It is well known the NV40 cores were not to keen on running and living with the higher Vcores.

It is better to go easy on the Vcore at first until more data is available.

Viper
08-19-2005, 03:47 PM
maverik-sg1

fair commetn viper J - thanks for the heads up. Mav
08-19-2005, 07:15 PM
MUCHO

Are these the same mods just wired different? I'm too noob to tell :(

http://www.ocxtreme.org/forumenus/sh...07&postcount=1
08-19-2005, 08:08 PM
ViperJohn

Quote:

Originally Posted by MUCHO

Are these the same mods just wired different? I'm too noob to tell :(

http://www.ocxtreme.org/forumenus/sh...07&postcount=1

Yes with just a dumb ground connection. The ground plane on the card and chassis ground are the same thing just two different places.

Viper
08-20-2005, 10:38 AM
maverik-sg1

using a 200ohm resisitor as advised - what is the max voltage you can produce at the full 200ohms?

Can anyone advise the voltage at given resistances (25ohm, 50ohm, 75ohm, 100ohm, 125ohm, 150ohm, 200ohm etc....)

A nice voltage versus resistance guide would be most excellent.

Cheers

Mav
08-20-2005, 10:53 AM
maverik-sg1

2fast for you over at another forum posted

"Card testing is all done and vmods are good and stable at 1.804 VGPU / 2.25 VDDR"

But I think he is using a waterchiller to -16 - it's a safe bet that 1.6ish volts is the max for water probably 1.5ish for air?
08-20-2005, 12:02 PM
harleybro

I hd no problem doing around 1.75 or so on ice water. Now all these posts about running 1.8v doesn't OVP kick in around there?
08-20-2005, 12:52 PM
maverik-sg1

Quote:

Originally Posted by harleybro

I hd no problem doing around 1.75 or so on ice water. Now all these posts about running 1.8v doesn't OVP kick in around there?

Interesting 1.75v on ice water so i am guessing water temps around 16degrees, what clocks were you able to achieve?

What volts did you settle for for 24/7 watercooling?
08-20-2005, 06:43 PM
Gogar

Quote:

Originally Posted by maverik-sg1

using a 200ohm resisitor as advised - what is the max voltage you can produce at the full 200ohms?

I hope you realise that low resistances produce higher voltages, for all i know 25ohm could kill the card instantly.
Be careful! Always start out with the highest resistance.
08-20-2005, 07:30 PM
ViperJohn

Quote:

Originally Posted by Gogar

I hope you realise that low resistances produce higher voltages, for all i know 25ohm could kill the card instantly.
Be careful! Always start out with the highest resistance.

It would lol.

Viper
08-20-2005, 07:35 PM
ViperJohn

Quote:

Originally Posted by maverik-sg1

using a 200ohm resisitor as advised - what is the max voltage you can produce at the full 200ohms?

Can anyone advise the voltage at given resistances (25ohm, 50ohm, 75ohm, 100ohm, 125ohm, 150ohm, 200ohm etc....)

A nice voltage versus resistance guide would be most excellent.

Cheers

Mav

You can't do it that way. Tolerances in the regulator and components allow a fairly wide range in the Vcore at a given resistance.

So far with stone stock card I have seen the 1.4 vcore vary from 1.409 to 1.446.

You do not go by resistance, except for installing the pot at max resistance initially, or by counting pot turns. You use a known accurate DVM. If you do not have one you should not be volt modding anything.

Viper
08-21-2005, 03:07 AM
maverik-sg1

I see your point viper J, my cards are set in SLI and I struggle for space to get the meter in when inside the case, so setting the resistance to a predetermined level would be ideal for me - but it's not impossible to do each card on there own first, volts to be adjusted in windows not BIOS or DOS right?

Got me a DVM which is accurate - max volts looks like 1.5v on air (very good air cooling that is) 1.65v max on water (although 1.6 for 24/7) and 1.8 volts for subzero cooling.

Just to clarify one thing - when these are installed the resistor is set to max resistance for normal volts and then resistance is lowered to increase the volts to the core?

Cheers

Mav
08-21-2005, 03:33 AM
Tamille

Quote:

Originally Posted by maverik-sg1

Just to clarify one thing - when these are installed the resistor is set to max resistance for normal volts and then resistance is lowered to increase the volts to the core?

Yes that is correct lower the resistance to get higher voltages.. I run my card at 1.7v when bench testing and 1.48v for everyday use. I did leave the voltage at 1.74v for 5 day 24/7 untill I realized and then lowered the voltages again. Normal watercooling.
08-21-2005, 05:35 AM
maverik-sg1

Quote:

Originally Posted by Tamille

Yes that is correct lower the resistance to get higher voltages.. I run my card at 1.7v when bench testing and 1.48v for everyday use. I did leave the voltage at 1.74v for 5 day 24/7 untill I realized and then lowered the voltages again. Normal watercooling.

Excellent - what watercooling are you using (blocks rads etc..) and what temps do you get under load at those voltages?

What clocks have you been able to achieve?

Cheers

MAv
08-21-2005, 10:24 AM
ViperJohn

Quote:

Originally Posted by maverik-sg1

it's not impossible to do each card on there own first.

Mav

That doesn't make any sense. Mod one card at a time then volt set then find the OC for it. Mod the second card and do the same thing on it's own.

After you have the OC's for both remember the OC for the slowest card and run both cards at that when you setup the SLI.

Yes you set the Vcore in Windows. You have to have the Windows drivers loaded as it is the drivers that read bios voltage table and actually set the cards Vcore as the operating mode changes (2D - LP3D - HP3D )

Viper
08-21-2005, 04:01 PM
Tamille

Quote:

Originally Posted by maverik-sg1

Excellent - what watercooling are you using (blocks rads etc..) and what temps do you get under load at those voltages?

What clocks have you been able to achieve?

Cheers

MAv

eheim 1250
gpu = Silverprop Fusion HL
cpu = Silverprop Cyclone Evolution SE
rad = Black Ice Extreme II
temps are a max of 40~ full load.

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