Gonna do a Vgpu mod, see if this all looks okay

[TooDen]

This is a PM that I sent to Hell-Fire because he seems like the volt mod masta of disasta (disaster in a good way that is :) )


Im gonna perform the Vgpu mod on my 9800 pro myself, but before I do this, I just want to run all my supplies by you and see if you can give me any tips.

Here is the guide I am gonna use.

http://www.fastlanehw.com/reviews.php?action=view&revid=74&page=1

I've been practicing soldering on an old modem, and I have basically perfected attaching a copper wire to a tiny metal contact point, very VERY similar to the size that I will be soldering on the 9800p.

I am using a Radio shack 15w soldering iron,
Some Solder, size .32.
24 guage wire.


When I perform the mod I am gonna solder to the the solder point showed in this pic
http://home.comcast.net/~toodles1337/9800P_vgpu_copy.jpg

I am then gonna solder the other wire to the large ground point on the right, right below the vgpu read point.

Ill solder the wire that is going from the main point to the middle pin on my pot, and the ground wire to one of the outer pins.

I hope that seems like a good plan. Before this is all done I will check the resistance on the 2 pins i am going to use. I want it to come up as 10k. Which is max resistance that way my vgpu isn't affected very much at all. I will then slowly raise the resistance and keep checking the vlots to see the increase until I am satisfied.

Here are some of my main questions. I have been practicing using a double AA battery to see how the resistance affects the voltages. The stock volt on the battery I am using is 1.595v. When I touch it to the pot, and then check volts, it will be at 1.595. But when I turn the trimmmer wheel, the voltage will only decrease, and will never go above 1.595. Is this because batteries are made to not overvolt? If that isn't the case, then did I buy the wrong pots? http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=271-343

After I succesfully do this, I'll move on to the memory voltage mod.

Does this all look good or is there any redflags thats stick up?

[Jimbo Mahoney]

An AA battery will only ever supply 1.595 volts, or less if you put a resistor in series with it (as you have done).

The reason the volt mod works on the Radeon (apologies if you already realise) is the voltage control chip uses resistance as a measure of how much voltage to supply. Lowering the resistance tricks it into supplying more and vice versa. (Chances are this is technically incorrect, but it's the way I look at it).

[G H Z]

Yeah Jimbo is correct.

Resistance is exactly that RESISTANCE. When put in line with a power source such as the battery, when you increase the resistance the measured voltage will decrease. That is what you have seen and that is what should happen.

The way the mod works is by creating resistance on the proper circut of the IC, dropping that sense voltage will induce a GPU voltage output increase.

Everything looks good, my only suggestion is that if you are still not comfortable, then try doing some mod's on an old card that you dont care about.

[TooDen]

I don't really have any old cards that I could actually use to test a volt mod. But I have got my saudering down to an art form. I can sauder a wire to a PCB in a very very very small little square.

My vmod will be done on Friday. Just Vgpu to start. Next I'll move on to Vmem. One Q I have though is why would you want to use a 20k resistance pot on the vmem opposed to a 10k. So you can finer tune the voltage, to a much smaller decimal? Or is it the exact oppisite?

[Hell-Fire]

What everyone said above is true.

A resistor, resists current flow. Do not confuse current with voltage.

current = voltage / resistance.

Anyway, in my opinion, that is the best guide to follow when modding a 9800Pro. It is very well written, and with tons of pics to validate what he is saying.

I would certainly use the solder points versus soldering directly to the Vreg's. If you are going to use the ground point that is just below the Vgpu measure area, be sure to cut the bottom leg off the VR as it may touch that other point just above the Vgpu measurement area. I dont recall off the top of my head what it is for. Just always better safe than sorry when it comes to potentially causing and issue by connecting to something that isnt needed.

I would add some wires to the voltage check point to make taking readings easier.

No, a larger resistance on a VR makes fine tuning harder. The reason is this, say you take a 10K 15 turn VR...then each turn is approx 667 ohms...but for a 20K 15 turn it is approx 1.34K ohms. Fine tuning is harder when each turn yields a larger drop/increase in voltage. Now, if you have a VR that has more turns available, that would make fine tuning easier.

If you truly want fine tuning, then solder 2 10K VRs in a series and that allows a 20K resistance with 30 turns.

Hope this helps.

[G H Z]

Tooden

Vmem requires a higher resistance vr simply because the minimum resistance required (for most modders-some like crazy high voltage), for say 3.2v is OVER 10K. Maybe somewhere around 12-13K.

So obviously, if you were to use a 10K pot your new modded mem voltages would be well........you might smell something burning high.

[Hell-Fire]

Originally posted by G H Z
Tooden

Vmem requires a higher resistance vr simply because the minimum resistance required (for most modders-some like crazy high voltage), for say 3.2v is OVER 10K. Maybe somewhere around 12-13K.

So obviously, if you were to use a 10K pot your new modded mem voltages would be well........you might smell something burning high.

Not the case for this mod.

On the 9800Pro, with a 10k vr I barely hit over stock voltage with it set to max resistance.

That takes into account that he has already measured the voltage of his stock Vddr that is. If it is already over the Ati specs as set by the manufactorer, then yes, 10K isnt enough.

If his Vddr is around the stock setting of 2.9v, then 10K is more than enough. With it set to max resistance he should only see around 2.85-2.9v max.

If you are saying that he needs more than 13k to stay below 3.2v, you are mistaken. He can easily hit 3.2v with a 10k vr, not to mention that 3.2v is perfectly safe as long as there is decent air flow in the case.

Ultimately it is up to him to take the proper precaution of measureing his stock voltages for Vgpu/Vddr and making the proper adjustments if they are well over spec.

[TooDen]

Wait a minute... So, Right now I have my Pot set to 10k resistance. I thought this would change it as little as possible? but from what it seems like you guys are saying is, this exactly the oppisite, so that means with less resitance a lower voltage.

Now I am just confusing myself!! :mad:

Alright, so I took my multimeter and put it to the two pins i will use (middle and left). The resistance is 10.31k OHM or 10310 OHM. If I were to volt mod my card right now, would that set my VGPU to insta death volts?

Another tip I read somewhere is that you tin the wire, and then put solder on it for a second and it will then make it one solid strand. This may be wrong, but is there a way to do something like that?


Thanks in advance. If I understand the answers to these questions, I will be performing it tonight :banana:

[xbladex]

(so that means with less resitance a lower voltage.) NO


You need to set it to 10k resistance first then lower it to get higher voltage

[Hell-Fire]

Good lord!

If I gave you that impression, I apologize.

You should certainly sodler the VR on with it set to max resistance. That will give you just a bit over stock voltage. Then you lower resitance to increase the voltage.

Reread my post above. I state in line 2 that with it set to max resistance, I barely hit over stock voltage.

[TooDen]

Aight guys, thanks for the clearing that up. I got a little preoccupied tonight and didnt have time to do the mod, but I will do it tomorrow.


Oh, and these are my stock voltages:

Vgpu: 1.67v
Vmem: 2.89v

What are the 24/7 safe volt limits on a VGPU being cooled by water?

[Hell-Fire]

I wouldnt go over 1.85Vgpu. You can run maybe 1.9V for a 3DMark run or maybe 2, but I wouldnt push it much past that.

After shooting for the highest core and 3DMark score, I would lower it back down soon after....that is unless you are using a chiller.

That low Vgpu is a good sign that she may overclock well on the core side. The Vmem is pretty much right at spec.

[TooDen]

Ugh, I keep procrastinating!! I have a few more questions before I man up and do this thing. If even touch the PCB with a 15w soldering iron, will it die? I heard this happened to somebody on these forums.

I also heard someone say dip the wire in flux. Im not really sure what he means by this but I have stranded copper wire, and I want to make it one solid wire by soldering it. I thought flux was the 60% lead 40% tin wire stuff that I am using, but... maybe someone can clear this up for me.


Thanks... again and again for all the times you guys have helped me :D

[G H Z]

I would go find some 95/5 lead free solder, and flux is a must if you want any success at all. It is what makes the solder stick and flow into the connection. You cannot solder without it. It comes in many forms, but the best is the paste version imo.

Some types of solder have a "rosin core" which is simply flux put into the core of the solder wire. That works pretty good too, but not as good as a seperate flux. What is not to understand about "dip the wire in flux"??? You cannot be more clear. It coat's the wire with flux, then as you heat the wire/solder, they flow to together.

I really think you need to do some practicing before you try to mod your card. It sounds like you need it:D Just try tinning some wire ends to start. No need to do anything on the card yet. Just get the feel of what needs to happen to solder up some wire/connections.

And no the card will not die if you just "touch the pcb". You might be confusing that with the many people who have killed their cards by measuring voltages when the system is powered.....one little slip(short), is all it takes.

[TooDen]

Okie dokey, I get it now. I was just confused be cause of all these terms people were throwing out. I have rosin core and it automatically sticks.

Alright, I know all the info I need to know to be able to complete this mod. Now I just need to increase the size and weight of my balls :D

[rhino56]

with a 10k vr set all the way up, which meaures about 10.9k
on my 9800 pro 360 core i get 1.733 volts
whats up with that? shouldnt i be around 1.9?

[rhino56]

Ugh, I keep procrastinating!! I have a few more questions before I man up and do this thing. If even touch the PCB with a 15w soldering iron, will it die? I heard this happened to somebody on these forums.

I also heard someone say dip the wire in flux. Im not really sure what he means by this but I have stranded copper wire, and I want to make it one solid wire by soldering it. I thought flux was the 60% lead 40% tin wire stuff that I am using, but... maybe someone can clear this up for me.


Thanks... again and again for all the times you guys have helped me :D
flux is a paste that the solder will spread onto when melted.
and helps it hold better.

[STEvil]

with a 10k vr set all the way up, which meaures about 10.9k
on my 9800 pro 360 core i get 1.733 volts
whats up with that? shouldnt i be around 1.9?

no, around 1.73 with VR at max resistance is right. It will only increase as you decrease resistance of the VR.

[rhino56]

no, around 1.73 with VR at max resistance is right. It will only increase as you decrease resistance of the VR.
so what K is around 2.9V?

[rhino56]

dang im down to 5K and still only at 1.771V
lots of off and on to get this right.

edit: 4K = 1.790V

[rhino56]

okay well i tried a overclock with 1.790 volts and i gained about 20mhz on the core.
which is amazing really considering im only at ambient water cooling.
25.5 C

this card hit 497 artifact free at sub zero temps on the cryo machine.

this is what i got with the 1.790
:D :D :D :D :D :D
http://www.cryo-laboratory.com/upload/userfiles/rhino56/1.8volts%2025.5C.JPG

[STEvil]

so what K is around 2.9V?

10K for ram

GPU and RAM are not linked.

[rhino56]

10K for ram

GPU and RAM are not linked.
i meant 1.9V sorry

[rhino56]

3.5K gave me 1.8 volts