ATI 3850/3870 Voltmod thread

[Jimbo Mahoney]

Is there OCP mod required for these cards? I did vmod and it works fine but when I raise voltage to say 1.5v I cant run 3dmark even at stock clocks. It goes black screen. 1.4ish volts works fine.

Not normally. People have been running 1.9v without problems.

EDIT - hehe actually my Triplex 3850 does have OVP or OCP - I can't go above 1.55v without it shutting down.

[Eldonko]

Any of you have HIS card that can confirm working vgpu mod without ocp mod? I could do shams ocp mod here but I dont want to do it if unnecessary.

[ceemic]

1,90V should work fine without OCP. 1,9+V needs at least DICE. I have benched w/ 1,84V w/ Volcano12 in -4C ambient (I turned to 1,87V, but lowered "just in case" to 1,84V before benchmarking...)

[Eldonko]

Lol Im not planning on running 1.9v anytime soon. My problem is something is happening when I inc voltage to 1.5V even. Black screen the second the 1st test in 3dm06 begins even at stock clocks. Spent like 6 hours troubleshooting last night, and will continue today after work. Mod seems to be working fine, but now that I think of it the one thing I did do before testing was install the new 8.3 CCC. Maybe Ill roll back just to eliminate driver issue as cause.

[JamesBong420]

well feel around the card for hot spots. my mosfets get raggggging hot once i start going over 1.5v. i had to sink em and i still cant touch the heatsinks with my finger. GL

[Eldonko]

Yeah I was just keeping an eye on the ram temps because I just have a 120mm on it and no sinc but it wasnt too bad. Card makes a hell of alot of noise when its loaded tho lol.

[slugzkea]

Sorry for the n00b question but I've read in the past that a 2b pencil is what should be used for modding.

However, one of the main successors in this thread has used a 3B pencil.

I have a 2b, a 4b and a 8b pencil.

Which one should i use, should i go out and buy a 3B pencil?

THANKS

[Clint]

Sorry for the n00b question but I've read in the past that a 2b pencil is what should be used for modding.

However, one of the main successors in this thread has used a 3B pencil.

I have a 2b, a 4b and a 8b pencil.

Which one should i use, should i go out and buy a 3B pencil?

THANKS

The softer the pencil the easier to apply.

I use 4B, but I guess 8B is even softer due to the higher number.

There is also differences in how the graphite is applied.
Some stroke it with very small pressure, leaving a lot of graphite on there (gaining very low resistance) but also very easy to get blown off and stuck on other places (not good).

Some stroke it with more pressure and have to work harder to get the same low resistance, but it will not get blown away so easily.

In any case you should "seal" it with tape or nail coating to prevent it from get blown off.
As you might see, if using the "low pressure" method you will get a lot washed off when using nail coating.

Nail coating is that stuff women put on top of the red color to make their nails look all shiny and all...

I hope this cleared up some.

[pablo NZ]

ok so i just bricked my gecube 3850 by setting vcore to 1.42v

it worked ok for a while, but then it started artefacting so I removed the mod, then it started artefacting at stock, and now it even artefacts at 300mhz...

funny thing is though, on one occasion it seemed to work fine at stock clocks after all these problems, even getting through 20 minutes atitool artefact testing and a crysis benchmark at high settings with 4xaa. Leads me to believe it may be reversible damage, but who knows... :S

remember kids, all mods are done at your own risk

[pablo NZ]

Mod seems to be working fine, but now that I think of it the one thing I did do before testing was install the new 8.3 CCC. Maybe Ill roll back just to eliminate driver issue as cause.

My probs started right after going to 8.3 as well, could just be coincidence though....

I'll roll back and see if that does anything.

[Blackoberst]

I'm having some problems with my 3870. I was benching 985/2700 with vgpu mod and after a reboot I got no signal on my monitor.
I moved it to the second PCIX slot, plugged in a 6200TC in the first PCIX slot and it was detected in Windows. Gpuz detected the 3870 fine, the only strange issue was that the GPU load was at 99%.

The question is what's the problem? Video card 'almost dead'?
Any chance to be fixed somehow?

[victorbr]

can i use hot glue to fix the graphite??

[Riska]

Yes but clear tape is eayser

[kup]

Lol Im not planning on running 1.9v anytime soon. My problem is something is happening when I inc voltage to 1.5V even. Black screen the second the 1st test in 3dm06 begins even at stock clocks. Spent like 6 hours troubleshooting last night, and will continue today after work. Mod seems to be working fine, but now that I think of it the one thing I did do before testing was install the new 8.3 CCC. Maybe Ill roll back just to eliminate driver issue as cause.

I PM'd Eldonko this but I figured everyone might be interested...

About your black screen problem with 1.5v on your HIS card. I've got a GeCube O.C. Edition card which suffers the same problem ONLY when I use a HIS bios.

If I use the GeCube bios, or the Sapphire Bios I can push 1.5v+ quite happily...

Any thoughts anyone? I've tested this quite a bit and it's definitely the HIS bios that prevents 1.5v...

[Eldonko]

Very interesting, I think switching the BIOS is the only thing I didnt try. I was told that OCP cant be in a BIOS and it clocked well at stock volts so I didnt try any diff ones. Thanks for the heads up on that, will give a try.

[Eldonko]

The question is what's the problem? Video card 'almost dead'?
Any chance to be fixed somehow?

Sorry to say but no display with one card when another works fine usually means the card is done. Did you try removing the mod and see if it will give display?

[pablo NZ]

Ok so to serve as a warning to others (story of my life lol) I think my card is permanently damaged.

I pencil shaded my 512mb gecube 3850 from 1.26v to ~1.42v and everything was fine for a couple of weeks until it started artefacting. I removed the mod but it just kept getting worse. Now I can't even boot into Windows without having a 80mm case fan sitting on top of the card. Presumably the voltage regulator had its lunch

Works fine now, but can't resell it or RMA it, and I'm hesistant to even overclock it past factory settings (725mhz core). I have a couple of 3870's on the way so maybe I'll just go for gold and see what fun 1.5v gives

[Blackoberst]

Sorry to say but no display with one card when another works fine usually means the card is done. Did you try removing the mod and see if it will give display?

Yes, I've tried removing the mod, but still no signal.
It's strange it died so quickly, no hardmod, only vgpu pencil mod.

[Jimbo Mahoney]

Not normally. People have been running 1.9v without problems.

Hehe what do you know, I think my 3850 also has OCP /OVP (OVP I think).

It works fine at 1.5v but as soon as it reaches 1.55v, it drops to 0v and the screen goes black.

My card is a Triplex 3850 512MB using a Nexsem 2415:

http://www.nexsem.com/pdfs/2415DS.pdf



The blue circled resistor is connected to pin 8 (OCP) of the 2415. If I remove this resistor, I'm assuming it will remove the OCP? Looking at the section in the PDF, it seems increasing the resistance of this resistor will increase the OCP point, so removing it will do the trick?

EDIT - Removing this resistor did nothing at all. Card is fine and OCP still functions

[Nosfer@tu]

Anybody have the pictures for the 3870 OCP mod ?

Found it a bith further up

[kup]

Very interesting, I think switching the BIOS is the only thing I didnt try. I was told that OCP cant be in a BIOS and it clocked well at stock volts so I didnt try any diff ones. Thanks for the heads up on that, will give a try.

Have you had any luck with this, Eldonko?

[Eldonko]

Put the card back in yesterday to try this and it is just black screen when I boot.

[victorbr]

What is this OCP??

[kup]

Put the card back in yesterday to try this and it is just black screen when I boot.

Dead card or bad flash? I've found ATiWinFlash to brick my 3870 several times, had to boot with an x300 and the 3870 in the other PCIE slot and force flash it again...

What is this OCP??

Protection against overvolting. Hence we disable it and overvolt anyway.

[Eldonko]

Dead card. Worked fine last time I ran it but when I put it back in to flash a BIOS it gives no video.