Help on Trimpot knowldge

[MaddMutt]

I have purchased a 100K & 5K Trimpot for my HD 4870 Voltmod.
I followed the required items needed as found here http://sandwichamwin.blogspot.com/2008/07/volt-modding-hd4870.html

Both of the trimpots have their knobs on top. Which way does it need to be turned to be in the OFF\LOW position?? Does the knob stop turning when you reach the end??

Here are pictures of the trimpots that I got.

100K Trimpot


5K Trimpot


Thank You For Your Time

 

[Blaylock]

Those look slightly different than mine but probably function the same. for mine (10k) i had to have the trimmer turned fully clockwise(Max resistance) to set the vCore close to the BIOS setting. It probably depends on which two post you use on the pot also. You could always test it with a digital Ohm meter/multi-meter.

 

[Lochekey]

I use pots similar to this. Like Blaylock said it will depend on which leg you connect. The center leg is the common and the two outer legs are the varied resistance. Depending on which of the two outer legs you connect to you will either have to go clockwise or counterclockwise so it is really up to you how you want to set it up. I draw an arrow with a plus sign on mine so that i remember which way is which after i have them wired up.

 

[Blaylock]

^ This guy is smrt. I normally make sure to return it to the lowest setting before I'm done that way I'm not hammering volts while at ambient. LOL

Does the knob stop turning when you reach the end??

No it doesn't stop at either end but you can definitely feel when you reach the end. There is a tactile end.

 

[Lochekey]

^ This guy is smrt. I normally make sure to return it to the lowest setting before I'm done that way I'm not hammering volts while at ambient. LOL

No it doesn't stop at either end but you can definitely feel when you reach the end. There is a tactile end.

The ones I bought do have a end stop. If you overcrank them you can break past it but there is a definitive stop. I wire in a microswitch in my setup as well so that I can leave my trimpots set and just turn them on and off.

 

[Blaylock]

Something else to note MaddMutt is that even with the trimmer turned all the way down there was still a bump in voltage (0.064v) from the BIOS settings prior to adding the pot. Adding a micro switch like Lockekey may eliminate that, but it's something to be aware of.

 

[Lochekey]

Here is a link to how I set the trimpot and switches up. You can see my adventures into destroying one of my 7970s as well.

http://www.overclockers.com/forums/...-HD-7970-mod?p=7990428&viewfull=1#post7990428

 

[Johan45]

Just check it with your multimeter only way to be sure which leg is off/on and what restistance you're getting. If you don't have a DMM get one

 

[MaddMutt]

As I posted earlier. I'm following this guide to voltmod my HD 4870 http://sandwichamwin.blogspot.com/2008/07/volt-modding-hd4870.html

Hopefully it will not turn out like Lochekey's. I think a WILD cat hair might have caused yours to short

When using my DMM set @ 2K ohms and reading the 100k trimpot. Using the middle tab as common - The right tab reads .002 - The left tab reads .101 - Does this sound right??? I think this is turned all the way down for the middle\right tabs.

 

[Lochekey]

Can you set your DMM to 100k+ ohms instead of 2k ohms it will give you a more reliable reading.

 

[MaddMutt]

Can you set your DMM to 100k+ ohms instead of 2k ohms it will give you a more reliable reading.

I have above the 2k spot - 20k, 200k and 2m. 200k gives me - Left 00.1 - Right 00.0

Reading package and it says 100 ohms, would that be the setting below 2k that reads 200??? With this setting I get - Left 99.7 - Right 00.7

 

[Blaylock]

Set to 200k

 

[Lochekey]

Are you using 100K ohm or 100 ohm trimpots? The guide calls for 100 ohm and 5k ohm trimpots not a 100k ohm trimpot.

 

[MaddMutt]

I'm using 100 ohm trimpot for the VGPU and 5k ohm for the Memory side.

 

[Lochekey]

Ok earlier you mentioned using 100K ohm trimpots which is why I was second guessing your DMM readings. Based on this I would say that yes you have them set correctly all the way to one side.

 

[Johan45]

If you read 0.000 that side is off

 

[MaddMutt]

How much mv does the 100 ohm give??
How much mv does the 5k ohm give??
Does the increase mv show up in Afterburner\Trixx. Do you turn up the trimpot while the card is powered up??
I don't want to turn it to far and fry the card

 

[Blaylock]

I can't speak for the GPU, Lochekey is the guy for that, but on my mother board the Voltage change does show up in CPU-Z so I would venture to guess that it would for GPU-Z too. Turn the screws slowly to add just a little voltage at a time. Sometimes it takes a few turns before the voltage will start to change then just go slow.

 

[Johan45]

How much mv does the 100 ohm give??
How much mv does the 5k ohm give??
Does the increase mv show up in Afterburner\Trixx. Do you turn up the trimpot while the card is powered up??
I don't want to turn it to far and fry the card

Voltage increases depend on the initial circuit voltage
You'll need live voltage read points to to verify V_GPU and V_Vram look at this pic after I took it I added another lead for the mem voltage readings. This is a lot easier than trying to touch spots on the card while it's running in a system
http://www.overclockers.com/forums/...9800GTX-Vmod?p=7950661&viewfull=1#post7950661

 

[Lochekey]

My voltages do not show up in the software monitoring which is why I added the voltage readouts on the 7970 that I did.