9800XT Vgpu mod

I started a thread on the 9800XT Vdd mod: http://www.xtremesystems.org/forums/...threadid=20855.

I figured I'd start another thread for the GPU vmod. The PWM controller on the 9800XT is different from the 9800pro, it's the Fairchild FAN5240MTC, http://www.fairchildsemi.com/pf/FA/FAN5240.html. I've just started studying the data sheet, but the interesting thing about this part is that it's original intended application was as a two phase PWM controller for the AMD mobile Athlon and Duron processors. Voltage is supposed to be adjustable from .0.925V to 2.00V, with a 5 bit input for voltage selection. If we're lucky it might be possible to control these directly, although some may be tied directly to ground, which would complicate things.

Anyway, I thought I'd pass on this info so we can get started working out a mod. Hopefully I'll have some time this weekend to work on it.

keep up the good work, I am sure alot of people are waiting for the results ;)

Here's more information on the 9800XT Vgpu vmod. As mentioned above, the 5240 controller has 5 voltage select pins, VID4-VID0. The 9800XT has them hardwired: VID0,VID1 and VID4 are grounded and VID2 and VID3 are high. This normally gives an output voltage of 1.40V. However, unlike the example circuit in the data sheet, the 9800XT has a resistor between pin 17 and pin18 (VcoreD and Vcore+), as well as the series resistor between pin 18 and the Vgpu voltage. The resistor between pins 17 and 18 results in a voltage drop from Vgpu to pin 18. On the 9800XT the resistor between pins 17 and 18 is R1591 and the series resistor is R1592. The Vgpu voltage is thus:

Vgpu=1.40x(1+R1592/R1591)

The original resistor values are:
R1592= 432 ohms (62A code)
R1591=1620 ohms (21B code)

This give a default Vgpu=1.4x(1+432/1620)=1.77V. The measured value is 1.78V, which is excellent agreement. To increase Vgpu the easiest approach is to reduce the resistance between pins 17 and 18 by carefully connecting a pot across R1591. I'd suggest using a 20K pot. When the pot is at 20K, Vgpu would be 1.80V. The pot would be at 7.9K for 1.85V and 4.8K for 1.90V. If you want to go above 1.90V, a 10K pot might be a better choice.

Here's a picture showing the connections for the pot as well as convenient points for measure Vgpu. (Sorry for the crappy picture quality.)

Great Info, BMG!!!
Thanks. I'm sure someone with a SUPER digi cam will come along and do a close-up of the resistors in question and then we will ALL be brave enough to try the mod!!
C

Nice ! but if it was me that just got a 9800 XT i wouldnt have the nerves to vmod it ! :D

Hi Bmg is it possible to just change the SMD resistor like you said in the vmem mod??
( I'll most likely just replace the 562 ohm resistor on the board with a 487 ohm (for 2.98V) and then remove the wires.)


Please help me if you can!

Quote:

---

Originally posted by Riska
Hi Bmg is it possible to just change the SMD resistor like you said in the vmem mod??
( I'll most likely just replace the 562 ohm resistor on the board with a 487 ohm (for 2.98V) and then remove the wires.)

Please help me if you can!

---

YGPM.

I have Pmed you back!!

Bmg have you read my PM?

I can't take a good picture but here's mine for those PMing me.

OPP

I have had my GPU up to 2.1v
Memory up to 2.9v

Card still works fine.

What volts you guys run up to?

Quote:

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Originally posted by FUGGER
I have had my GPU up to 2.1v
Memory up to 2.9v

Card still works fine.

What volts you guys run up to?

---

Is that a typo, or are you just really conservative? :D

Maybe he meant 3.9V, lol

C

Quote:

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Originally posted by charlie
Maybe he meant 3.9V, lol

C

---

The memory spec is 2.80+/-.15V, but the default voltage is around 2.68V. I've found cases with my two 9800XT's where increasing much above 2.8V actually increased artifacts. This was gaming not necessarily benching. While running Unreal2 my first 9800XT had fewer artifacts (sparkle) as mem voltage was increased. I ended up running it at 3.0V. However, when I was playing Halo I had sparkle artifacts in some places, and reducing voltage below 3.0V reduced the artifacts. I ended up running at 2.85V as a compromise. My second 9800XT has much better performing memory than my first card, but I don't see a lot of memory improvement as memory Vdd voltage is increased. I'm wondering if Vddq or Vtt is limiting my second card. The core definitely isn't the problem.

BMG,
My current XT, the one that is a lousy performer will give a hard lock at everything above 466....how does that compare to your XT's out of the box?

C

Not a Typo, thats all I need to max the memory out at ~451Mhz +-5Mhz

My current GPU block running R410
http://fugger.netfirms.com/gpu2.jpg

Fugger, have you tried out the new toy yet??? Awfully pretty!!

C

yep

wow thats one shiny umm....evap head...


is there a VDDQ that might be holding the mem back? I know the VDDQ is a problem on my 9800p mem, stuck at 378 :(

hey opp,
It looks as though you've used a different resistor than bmg???

Did you solder to the ass end of the fat tan resistor on the end closet to the controller??

http://home.comcast.net/~rbmccall200...8/site1501.jpg

:D

where the voltage measure point for the gpu???

Quote:

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Originally posted by Boogotop
where the voltage measure point for the gpu???

---

Check out the picture with "Vg" written on a piece of tape. At the tip of that tape there's a feedthrough without any solder mask on it. That's connected to Vgpu.

Quote:

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Originally posted by bmg
Check out the picture with "Vg" written on a piece of tape. At the tip of that tape there's a feedthrough without any solder mask on it. That's connected to Vgpu.

---

thx my friend!

Does someone have a picture close up of the whole thing. Without tape covering the resistor?

so basically, with a 20k pot, its impossible to adjust the voltage to the vGpu voltage any higher than 1.9v? reason i ask is because im a n00b to this and was worried about over adjusting the pot and frying my chip.

if i cannot go any higher than 1.9v using a 20k pot then i would consider that the safest route. any comments?

Ok after I finished the volt mods and this is what I got;

Out of the box the ATI 9800xt card did 435core/390mem @ stock volts(1.77Vgpu/2.70Vdd) @52c Load

With Swiftech MCW50/no ramsinks ->470core/390mem @ stock volts @38c Load

With Swiftech MCW50/ramsinks ->490core/400mem @ 1.94Vgpu/2.95Vdd @42c Load

This is the best I can do 490c/400m with no dots or artifacts. I was able to run 3DMARK2003 all the way without crashing at 520c/440m but massive dots/artifacts. I had the mem volts up to 3.31volts but could not run clean past 400 no matter what the volts. Do you think I need to do Vref mod to get past 400mem??

Also any volts over 1.94v to the GPU would lock up on a full 3DMARK run and i would need to reboot computer. In fact Vgpu would go "0" volts.

After testing this is what I found:

Vgpu Idle -- Vgpu Load
1.85v ------ 1.81v
1.87v ------ 1.84v
1.90v ------ 1.88v
1.91v ------ 1.90v
1.92v ------ 1.92v
1.93v ------ 1.96v
1.94v ------ 1.98v
1.95v ------ 2.03v <-- lock up on 3dMARK Drops to "0" volts.

What do you think is causing the voltage to jump under load??
What can I do to stablize the voltage??
My thinking was to step up to the MCW50-T to stabilize the voltage by keeping the core cooler but under load the temps are higher then stock heat sink.

By the way this is an excellent, extremly Knowledgeable forum. Thanks.

Well m8's i was reading bmc thread...
First of all i would like to thanks to bmc for such a nice thread...
Keep the good work m8...
Now let me explain my problem...
Yesterday i decide to do the vgpu and vddr mod to my 9800xt from hercules...
First off all i read the values on the multimeter for the gpu and mem's...
Gpu - 1,80v
mem - 2,7v

Then i took the card from my case and i start doind the mod's...
(I will put pics of it later for u guys can see the mod's, let me say sorry right now for the quality of the pics:( )

I finished all the mod...vgpu,vddr,2switch's on/off for each one and i did two points of reading the voltages with two 3pins fan conectors that i put in the card...

Everything pretty till then:) ...

Now this morning i connect the card to my pc, everything ok with image...i enter to windows then i remeber to see if the connections for the readings were working...
I've checked the vddr poit...OK, then vgpu point........1,434V????
I said to me...That can't be possible...
Read again...same value...
Then i read directly on the 9800xt voltage point reading...same value...
Then i remeber...maybe the 1,434v is the value that bmc refer here:
"This give a default Vgpu=1.4x(1+432/1620)=1.77V.The measured value is 1.78V, which is excellent agreement."
Then 1,434x(1+432/1620)=1.8164V
Then i said to mee...ok that's very possible that i'm thinking ok...
Then i put the swith on( i used a 10k pot [is regulated to 10k] ) and the value on the reading point was 1,49V...then 1,49x(1+432/1620)=1,887V
Then i said...Ok i guess i'm thinking ok...
Then i switch off the mod...
I enter ut2k3 to see if graphics was ok...
Now...the problem is here...
In Antalus (the level i tried) is with a little bit of small white dots around the screen...
I said...WTF????
I turn on the vgpu mod then....all dots disappeared :eek:
Then i said again WTF????????????????
Turning on/off the mod of the mem's is the same...only vgpu mod is directly doing something to the dots...
Now finnaly conclusion...
I have two questions...
First off all why was i able before the mod read the voltage correctly in the reading point of the gpu and now not?????
Second...Why the hell with the vgpu off i'm having white dots????
The problem is not using that voltage in the gpu...i ws thinking using more,but i would like to try at least understand why the hell this is happening....
Sorry for the long thread m8's...
Hope someone could help me figuring out this problem....:)
Offtopic...sorry for my english a little bit rusty:rolleyes:
Cumps
Vortan

What it sounds like is that the original resistor between pins 17 and 18 was damaged, or at least it's apparently not making contact with the pcb pads it was originally soldered too. Thus, when the pot isn't connected you'll get the 1.4V, as you already concluded. The problem with the white dots is consistent with low voltage. I'd suggest checking the resistors you soldered to. Too much heat when soldering to the resistors can cause the metal pads on the ends of the resistors to come loose. When that happens the resistor must be replaced (or leave your pot connected all the time).

Pic's of the mod's here...

http://www.pcdiga.com/Imagens/9800xt%20mod's.jpg

http://www.pcdiga.com/Imagens/9800xt_final_mod's.jpg

Maybe the solution is to unmake the vgpu mod and do it again...i will check later.

Bmc...could u put a pic of the resistor between pins 17 and 18 or edit one for i check in my vga????THKS

Cumps
Vortan

Well problem solved...
I enter to ut2k3 open my chieftec and two little touches in one of the vgpu wires mod and that's it...
Mod on or off no more weird white dot's and the vgpu reading is correct now...
Thks bmc:D

See here the pics of what was happening to me...

vgpu on:
http://www.pcdiga.com/Imagens/vgpu%20on.jpg

vgpu off:
http://www.pcdiga.com/Imagens/vgpu%20off.jpg

Well it's fixed, that's what matters...
Thks again

Cumps
Vortan

§§§§ it's not Bmc but Bmg OMG damm...
sorry m8
Thks:D :D :D

Mod's modified's...
This way i can read more easier the voltages :cool: ...

http://www.pcdiga.com/Imagens/VoRtAn...nd%20molex.JPG

http://www.pcdiga.com/Imagens/VoRtAn...0mod&#39;s.jpg

Regards

nice mod there bro. just finished getting my card modded at 1.9v core. it did 465 with stock voltage/cooling. now its hitting 480 with stock cooling. amazing thing about this card is its a refurbished card and the memory does 420Mhz in 3dmark2001 with stock voltage and cooling! amazing... im wondering if the Vddr will even help. im about to throw a swifft TEC on the GPU, and hope for atleast 500. then i should be able to bring my vgpu to 2.0v.

i wanted to ask you guys, is the Vtt, and Vddq needed? what is it good for?

I did the mod a little different from VoRtAn_MaDgE. I just soldered the joints to a 3pin female fan header & then solder the 10K pots to the male fan header so I can unplug it whenever I want.

Similar to "Creative's" mod but a little diff again, wheras he just plugs in his pots directly into the female fan header.

Couldn't be bothered taking pics atm as it's a mess, I've basically left the wires hanging everywhere.

Gonna do it up properly once i do the R1596 mod as well.

It's just a pity I start getting atrifacts at 460/780-790 with or w/out the VRs on.

Measured 1.85vgpu/2.85Vdd with 10K VR so I tried some 20K VR but still no go. Will try again later with more volts on Vgpu/Vdd....

Maybe it might be because I'm using the stock hsf but many have gotten higher with their stock hsf....

Oh well, guess I got a stinker....Won't stop me from trying til she's dead though....

Is there any alternate vgpu reading spot??? im vmodding my friends asus card and it doesnt have that little hole. Everything else is the same though, just dont have a gpu read spot, perhaps i'll have to just calculate vgpu by resistance values?

Grab a multimeter and start searching m8...default is approximatelly 1,8v...
Never see an asus pcb of 9800xt...
Regards
Vortan

Yeah thats what i was afraid of, hate to probe around tooo much on a $500 card i mean soldering is fine lol but my dmm scares me.

I was making a quick search to see if i can help u...
Tell me if this is the case:

http://www.xtremesystems.org/forums/...&postid=299338

If that's your layout check here the voltage measurement...

http://www.xtremesystems.org/forums/...&postid=299339

Regards
Vortan

yeah, thats the asus, but the reading points shown there are in two different spots, Cath22 just gave me a alternate place to read it, but its gpu under load so its gonna read a little low.

on the first picture of this thead by bmg is the black wire leading to GND?
I also dont see a measuring point for vgpu

the red and black wire go to a 10k ohm potentiometer, and the vgpu reading point is marked with a piece of tape that says VG

the black one goes where Pin 1 or 3 ?

color doesnt matter, simply run pin 1 & 3 to the middle and either other pin on a 10k potentiometer. make sure you set the pot to 10k ohms and bring it down slowly

anyone know of a Vtt or Vref mod for this card?

PM Catch22@Play hes the man when it comes to vmods. Why does one need more vmods? I have been fairly successful in overclocking my 9800xt with just good cooling and vgpu and vddr mods.

I already ask that to catch22@play in other thread( he's always trying new mod's or another ways of killing his car LOL) and he told that nothing proves till now that the other two mod's that were in 9800pro are usefull in this card.

hmm, i havent done the vddr yet because my memory runs 415 benching, and 400 gaming. core is set to 2.9v and does 475 stable gaming/benching on stock cooling. i put a TEC on the GPU, and as soon as my board comes in, we shall see what this puppy does.

Quote:

---

Originally posted by VoRtAn_MaDgE
Well m8's i was reading bmc thread...
First of all i would like to thanks to bmc for such a nice thread...
Keep the good work m8...
Now let me explain my problem...
Yesterday i decide to do the vgpu and vddr mod to my 9800xt from hercules...
First off all i read the values on the multimeter for the gpu and mem's...
Gpu - 1,80v
mem - 2,7v

Then i took the card from my case and i start doind the mod's...
(I will put pics of it later for u guys can see the mod's, let me say sorry right now for the quality of the pics:( )

I finished all the mod...vgpu,vddr,2switch's on/off for each one and i did two points of reading the voltages with two 3pins fan conectors that i put in the card...

Everything pretty till then:) ...

Now this morning i connect the card to my pc, everything ok with image...i enter to windows then i remeber to see if the connections for the readings were working...
I've checked the vddr poit...OK, then vgpu point........1,434V????
I said to me...That can't be possible...
Read again...same value...
Then i read directly on the 9800xt voltage point reading...same value...
Then i remeber...maybe the 1,434v is the value that bmc refer here:
"This give a default Vgpu=1.4x(1+432/1620)=1.77V.The measured value is 1.78V, which is excellent agreement."
Then 1,434x(1+432/1620)=1.8164V
Then i said to mee...ok that's very possible that i'm thinking ok...
Then i put the swith on( i used a 10k pot [is regulated to 10k] ) and the value on the reading point was 1,49V...then 1,49x(1+432/1620)=1,887V
Then i said...Ok i guess i'm thinking ok...
Then i switch off the mod...
I enter ut2k3 to see if graphics was ok...
Now...the problem is here...
In Antalus (the level i tried) is with a little bit of small white dots around the screen...
I said...WTF????
I turn on the vgpu mod then....all dots disappeared :eek:
Then i said again WTF????????????????
Turning on/off the mod of the mem's is the same...only vgpu mod is directly doing something to the dots...
Now finnaly conclusion...
I have two questions...
First off all why was i able before the mod read the voltage correctly in the reading point of the gpu and now not?????
Second...Why the hell with the vgpu off i'm having white dots????
The problem is not using that voltage in the gpu...i ws thinking using more,but i would like to try at least understand why the hell this is happening....
Sorry for the long thread m8's...
Hope someone could help me figuring out this problem....:)
Offtopic...sorry for my english a little bit rusty:rolleyes:
Cumps
Vortan

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I had the exact same problem. When I did the mod the resistor had lifted from the original solder pad and gave me only 1.4 volts. A tiny dab of solder and a steady hand and all is back to normal.

Tyberius I know how to mod ^^ Just dunno which end of the resistor I should solder to which pin

ok then, with the potentiometer, all you gotta do is make sure you use the center pin, and either of the side pins, doesnt matter which one you use. And you should be good to go, dont mean to sound condescending, just didnt know how much you knew about it, question though, what kinda cooling you got on that A64?? my watercooling has reached its limit and i need to go phase change....

im using an unmodded Mach II :)

The center pin definatly goes to the PCB of the graficscard pin 1 or 3 then go to GND... on which end of the transistor should I solder the middle pin to? for vgpu mod

Okay, for the vgpu mod, this is the best info i can give you, i assume you already know the area in which you have to do the mod...so heres a drawing i did.
http://www.geekextreme.com/images/li...9800XTVGPU.JPG

Perfect =) that clears up everything mate

Charlie did it differently tho he soldered Ground to R1592 I think

Damn cant add a pic to a already posted thread...
heres the pic of charlie
anyway I will do it your way tyberius :) thanks for the info

yeah, i dunno about that one, i suppose it'll work, but im fully comfortable soldering on SMD resisters, so i dont care, i know the way i did it worked beautifully, only thing that got complicated was Vmodding my Asus 9800xt, had a slightly different layout than my BBA, no vgpu read point...but my man Catch22@Play helped me out with that one

well I did both mods sucessfully..
VGPU is at 1.9 and VMEM is at 2.95
but theres basically no overclocking difference then without the mods...
Before I was able to get 526.5/ 425 on my Mach II ST Mounted on the GPU now
with the mods I am able to get 526.5 / 440

Both readings are accurate.. mods were done correctly and with success the reading points show Vgpu 1.9 and vmem 2.95 so it works but at 3dmark01 Im getting heavy artifacts at 534/430
with the same card a guy got 610 / 440 out of it using vmods and an Mach II
according to rivatuner the card is around 0 °C so I do not think temperature is a great problem.. my multimeter says that the core has -10 °C or so...

Well, you didnt really raise up the voltages all that high from stock. I have an engineering sample ATi 9800xt and the stock vgpu was 1.85v and the mem was 2.85. I run my vgpu at 2v and my memory at 3.0v even, and im just liquid cooling the gpu and active cooling the ramsinks. Backside of GPU isnt even warm to the touch. Helped greatly for me, both the added cooling and the vmods that is...dont know what one helped more as I did both almost at the same time. 535gpu/420 ram. What are you using to cool your ram????? I went overboard on RAM cooling and I cant get that high, yet. Check it, this was my card before my vmods. PS: you sure your ram clock being that high isnt whats causing your artifacts?
http://www.geekextreme.com/images/li...res/XTside.JPG
http://www.geekextreme.com/images/li...tures/XTx2.JPG

rofl sick man :) I was able to hit 585 / 438 today..

VERY NICE! What'd you change? Increase the vgpu voltage I'd suppose?

well Like I said the vmem wasnt working quiet well , I expected too much at lower voltages which made me drop back a bit..
So I unsoldered the vmem mod and just did the GPU I was able to hit 27.5 k with 2v on GPU
I then increased to 2,05 on GPU and redid vmem mod and im running 3.25 without 3,3rail mod :) I love my PSU and was able to get 438 MEM

With the rail mod I assume I would get further, right now im on 27,9 k in 3dmark01

:slobber: :slobber: :slobber: Ummm....I hate you.....j/k :p: Wow impressive, I guess I shouldnt complain, 25k on a koolance liquid cooling system isnt bad :D

Where did you get those little fans?

Ummm, I dont remember exactly, just google 20mm fans, you should find em. They were only $4 each, but last time I checked they were all sold out.

i just did this mod and when i measure the voltage with the mod off (i have on off switch) it gives 1.41v, when i measure voltage with mod on resistor set to 10k ohm, it gives 1.47. are these values correct. or do i substitute them for the 1.4 in the equation Vgpu=1.4x(1+432/1620)=1.77V to get my actual vgpu?

ok wtf... without the mods i could get 470core with the mod i cant even run stock XT speeds without artifacts
looks kinda like what VoRtAn_MaDgE was getting, but my artifacts dont go away when i turn on the vgpu, they actually get worse. whatd i do wrong (also i modded the card the way tyberius posted)
Ok i just tried upping the voltage and now it reads 1.5v and the white dots went away at stock speeds, but if i try to overclock at all it artifacts like mad

i just upped it even further so it reads 1.58v, i dont think it did hardly anything to the oc, actually it helps minutely. but still i cant overclock anywhere near what i could before the mod.

i think i figured it out. it WAS actually running at 1.4v originally i must have accidentally unsoldered that one resistor. i upped the resistance till it read 1.8v and now it works just like it originally did. strange but it seems to work.

Remake the gpu mod buddy...
Something is wrong there...
i had the same problem but fine now.

well i upped the vgpu to 2.0v and now i can go 500core with no artifacts. i think its working, but i think its just that little resistor must not be connected on both sides causing the stock voltage to be really low. now i worry though, if that were to just touch randomly sometime itd fry my card. so i think im gonna take it out a fix that, then it should be good.

Hi guys, tried that mod on a Asus 9800xt VIVO and it totaly got f**cked! I'm trying to see whats going on but both R1591 and R1592 are same Ohms!

I removed the mod, same thing...

System doesn't boot... mobo/drives are running normaly but nothing else.

Plz any help really appreciated,
Cheers,
Byron

Forget it, a mosfet on the card just went caboom!,
R.I.P.

More pics of Vgpu mod below, good close up (mine):

http://xtremesystems.org/forums/show...highlight=KODE