ATI 3850/3870 Voltmod thread

[K404]

Got 2 cards in this morning from AtomicPineapple for modding.

Measured the resistance between those points (FB to GND) resistance is 3.88K ohms, so pot value should be...80K I reckon

[TI66ER]

I had to turn mine down quite a few turns from full(100k) to get to 1.36v,so mebbe 80k is about right.

It works wonders tho'

Heres what i'm upto now-



i was putting a jumper on it last night so i can enable/disable the vmod and my gas iron ran out of juice,so i'll try some higher runs today.

[Cha0s]

I had to turn mine down quite a few turns from full(100k) to get to 1.36v,so mebbe 80k is about right.

It works wonders tho'

Heres what i'm upto now-



i was putting a jumper on it last night so i can enable/disable the vmod and my gas iron ran out of juice,so i'll try some higher runs today.

strange why do you get just about 11k points?
with same cpu speed and lower GPU speed i get 12400Points...
just my ram is at 1062

[Riska]

you have better driver settings than he has

[TI66ER]

What driver was you using cha0s?

And riska,were am i going wrong with my driver?

thanks guys

[Riska]

Have you set everything to performance?

[TI66ER]

Do i set that using the ccc?

Thx

[Norway]

Do i set that using the ccc?

Thx

Do you mind take a look and see ?

Yes it is in CCC and not hard to find ......

[K404]

*annoyed*

stock voltages for the cards im modding are 1.37/2.08V...seem higher than everyone elses??

Cards are Sapphire

[kemist]

*annoyed*

stock voltages for the cards im modding are 1.37/2.08V...seem higher than everyone elses??

Cards are Sapphire

I didnt measure mine pre-soldering, however, i measured with the resistance all the way up after the mod and i was getting a wide variety of values, with 1.4v in 3d, 1.3 something in windows, 1.26 on startup on one of the cards. Very weird.

[TI66ER]

Mine was 1.24v on bootup stock.My vgpu seems to stay quite steady at 1.36vgpu on 3dmark06.Temps max out at 54c.

Btw,thanks guys,i found the performance thing.What settings does it change?

[Riska]

It sets the quality of the displayed 3d graphics by the card more quality more power is used from the card tu produce it less quality less power is used

[TI66ER]

Well heres my new mod.





basically,the block with the trimmer on,plugs into the block on the card.there are two measure points on the trimmer block for measuring vgpu.I can disable it by just pulling off the trimmer block.

[K404]

72KOhms of res for the RAM gives 2.18V, so im gonna suggest a 100K pot for the RAM as well to get the lowest voltage possible reduced a bit. I think the cards I had were set higher than most, so maybe 80K will be fine for everyone else. Will update first post.

[TI66ER]

Heres mine in action-



I set the vcore to 1.34v and rebooted and removed the pot.The resistance at 1.34v is 61.2kohms

[Jimbo Mahoney]

Is there enough data yet to say what 3870s and 3850s typically clock to on the core with a Vmod?

It seems the 3870s can go to ~ 1Ghz on the core, while the 3850s go to ~ 850 Mhz?

[Vatos_locos]

no i have one 3850 and she can hit 1026Mhz on the core benchable

[pepinorang]

Is there anyone here ready to do the OCP mod on my 2 cards ? I haven't the necessary competences and tools to do it here and can't find anyone to do it for me in france

If there's someone interested send me an MP

Thanks,
Bye
p€p|n0r@ng

[Jimbo Mahoney]

no i have one 3850 and she can hit 1026Mhz on the core benchable

That's reassuring. I've seen one on OcUK go that high too.

Sounds like a winner in terms of bang for buck!

[Random Murderer]

Man, this thread sort of died.

To get it going again, how about you guys check out the pencil-mod guide I created over on TPU and let me know what you think?

[Norway]

died out

Soon I'll get 4 more 3870 card's to mod, but I can't keep them

[Hola77]

Hello people, this is my first posting at extremesystems. Been waiting for like 2 weeks to get permission to start posting. I need you experts to unleash my card which has given me a lot of sorrow.
I have a Gigabyte 3850 512mb (ultra durable 2). The problem is that it has a different PCB compared to the standard one and runs at lower memory speeds aswell (700Mhz). So I tried a pencilmod by reading some threads, but it didn't work because of the different layout of the PCB.
Now what really drives me insane is the different BIOS it uses. It prevents me from using any of the modded BIOSes.
I would like to ask if someone could take a look a my BIOS and raise the voltage to 3870 levels. It hasn't been done yet for this card and there are more people around the world who are aching to get a modded bios for it.
So please anyone who feels up to it, take a shot. It would be the first modded BIOS of it's kind I guess.

[Norway]

A voltmod (solder/pencil) would be a problem if you know how to find it ....

A BIOS change may be a little difficult, but if the BIOS dosen't have the 862Mhz limit then drop it and do a soldering vmod

All you need is to find the correct IC and find the FB pin, then solder a VR between and off you go :P

Value on the VR you need is the resistens between FB pin and ground x20 roughly calculated

FB = FeedBack

[Hola77]

A voltmod (solder/pencil) would be a problem if you know how to find it ....

A BIOS change may be a little difficult, but if the BIOS dosen't have the 862Mhz limit then drop it and do a soldering vmod

All you need is to find the correct IC and find the FB pin, then solder a VR between and off you go :P

Value on the VR you need is the resistens between FB pin and ground x20 roughly calculated

FB = FeedBack

Well I would kinda be more happy if someone could mod the voltages on my bios first.
I have very high hopes for this card, because the PCB is exactly the same as on the Gigabyte 3870 model. So I was hoping a bios mod could give me real 3870 voltages instead of the 1,28v all the other people with 3850 get.
By the way, my card is part of the "ultra durable 2" range. It has high quality components which reduce power consumption and heating. So this is another reason why I have high hopes for this card.

[MonsterMash]

Made pencil vmod, new vgpu is 1.512V .

This the results:

Freq. GPU: 1012mhz
Freq. RAM: 1301mhz x 2

3DMark06:



Crysis Bench @ 128x1024 all very high. DX10 on vista 64 bit:

================================================== ============
TimeDemo Play Started , (Total Frames: 2000, Recorded Time: 111.86s)
!TimeDemo Run 0 Finished.
Play Time: 110.36s, Average FPS: 18.12
Min FPS: 10.60 at frame 1942, Max FPS: 23.63 at frame 860
Average Tri/Sec: -12040729, Tri/Frame: -664394
Recorded/Played Tris ratio: -1.38
!TimeDemo Run 1 Finished.
Play Time: 103.22s, Average FPS: 19.38
Min FPS: 10.60 at frame 1942, Max FPS: 23.63 at frame 860
Average Tri/Sec: -12659318, Tri/Frame: -653346
Recorded/Played Tris ratio: -1.40
!TimeDemo Run 2 Finished.
Play Time: 102.75s, Average FPS: 19.47
Min FPS: 10.60 at frame 1942, Max FPS: 23.67 at frame 983
Average Tri/Sec: -12684731, Tri/Frame: -651668
Recorded/Played Tris ratio: -1.41
!TimeDemo Run 3 Finished.
Play Time: 102.24s, Average FPS: 19.56
Min FPS: 10.60 at frame 1942, Max FPS: 24.34 at frame 985
Average Tri/Sec: -12775948, Tri/Frame: -653119
Recorded/Played Tris ratio: -1.40
TimeDemo Play Ended, (4 Runs Performed)
================================================== ============

Max temp (@water cooling) is 40°C.
It seems to be RS.