7900 GS / GT Volt Mod

[Vatos_locos]

i have put some thermaltake ram heatshinks on the mosfets and the regulators on the back of the card on 2.2V on memory i couldn't go more than 900Mhz on 2.34 exacly i can hit 1Ghz so is it so terible ?

for the core under load i'am having about 60 degrees celcius for the core coolin on zalman VF900-CU LED but i'am going to put a Wb on her
you scared me i can say that i'am runing @ 2,3V now on the ram but on 1000Mhz i am having delta mismach on atitool
and the resualts are :

about 23K on 3D Mark 03 with my E4300 @ 3Ghz an my rams @ 1Ghz 4-4-4-14 i need a new psu tho

[ziddey]

do you have the fan on the vf900 on low or soemthing? I could have sworn I had much better temps than that when I had one on mine.

As for high speed ram, do some testing at 800mhz, 850mhz, 900mhz, and 1000mhz at your current core clock. You should see that the difference isn't so great. You should focus more on getting core to 700. Also, if you wish, you can fiddle with the geometric delta. I was able to run mine at +60.

[Vatos_locos]

the fan of the cooler is powered from the card i changed the conectors on @ 2D is running @ 25% on 3D @ 100%
you are right about the mem i did't noticed any difrent but i want the 1Ghz for the number call it fetish

as for the core i read that 7900's are not so hapy with 1,5 volts and the blow the core so i'am afraid to set 1,5 i might to a mod with a jumper tho and if i want to set the core to 1,5 just switch the juper

[ziddey]

1.5v to core with good cooling is much safer than the 2.34v you're pushing to the ram.

[Vatos_locos]

yes but the card runs hot for now is it safe to set the voltage @ 1.5 V
the ram voltage now is 2.3V not more not les the card runs good win no artifact @ 660/1000

what you sugest is it save the 1.5V on the core with my temps ? note that outside we have more than 40 C and i can't have the ac 24/7 open

ziddey
Also, if you wish, you can fiddle with the geometric delta. I was able to run mine at +60

mine delta is set to 20 (NiBitor) how soud i set it 20 + 60 = 80 ?

[K404]

Has anyone else ran into OVP trouble with their 7900GS? If I try 1.35V, the moment the card switches to 3D mode, I get a black screen. Below 1.35V, things are fine.

Does anyone know which SMC need removed for OVP bypass?

Cheers!

[ziddey]

I take it you don't have a reference board, or at the very least, are not using the common ink method?

Also, can you actually measure that in 2d mode, it's a different voltage? I haven't seen a 7900gs (at least reference pcb) have the components to switch voltage from 2d to 3d.

[K404]

Im using a pot connected using this pic as reference:



Reference design.

To be honest, no, there is no voltage change from 2D-3D, but its when the clockspeeds switch from 2D to 3D mode...same thing, more or less.

I chose not to use a 1.5V forced mod, I like having the element of control over my mods and voltages

K

Pic taken from Shamino/VR-Zone

[ziddey]

Hmm, well if you're willing to go the switch route, you can still have control, and have switches that flip open +0.1v, +0.2v, and +0.05v, so by varying the switches, you can get your control from the baseline 1.2v.

edit: just did a google search for 7900gt ovp and found a lot of results. http://www.xtremesystems.org/forums/...ad.php?t=92874 as a place to start.

but that's only if you don't consider my idea, although you'd be limited to combinations of the 3 increment amounts

hope this helps


edit again: http://www.xtremesystems.org/forums/...d.php?t=103890 that was something I've always been interested in myself, but too lazy to get around to. if once you've found your satisfied overclock, but want to keep low 2d volts, that's the method for you

[K404]

Thanks for the links I have some insight now into why the pic cupcake posted works

I might play with the BIOS to have a 2D-3D voltage switch in future. Shouldnt be too difficult.

thanks!

Kenny

[ziddey]

cupcake? i'm sure you know this already but just wanted to make sure by saying that you need to add components to allow the vid switching to work. good luck and post your results

[josty2]

I see that everyone is still loving the cards. I've got some here aswell, especially 7900GS cards.
They are quite amazing. If you OC them with 1.55v and some more voltage to the memory, they will easily own a 7900GTX for just over $100...
Really a good card to hold over till HD2950 or 9800gtx!
But the results here are very impressive!

[Vatos_locos]

any hard mod for the mem vr or something i flashed the card with edited bios so i need somthing stable on the mem :P

is this going to work or i will fry my vga

[ziddey]

that'd work but you will very very much so want to throw a sufficient heatsink on that ic next to it.

[Vatos_locos]

I have coolers on the card that'a not the problem
are you sure that this will work i don't wana fry my card couse i canot buy a new one

this is my card

[ziddey]

soldering a vr is no different than shading with pencil. if it were to break, it'd be from the overvoltage of course.

the card isn't bandwidth starved, so you dont need to push ram that much.

[Cupcake]

with a pencil I got up to 2.8v

I have to be careful when penciling my cards

[Vatos_locos]

ziddey thank yoy very much i'am going to buy some vr tomorow or the day after i will post my results

Cupcake i want the vr couse the boded bios on the vga and the pencil on some days is gone so the voltage is lower day by day

[dnarts]

hello boyz !

Thanx cupcake for a nice piece of information about 7900vmod ,

I got very sad problem :
I'm on rev.1 asus 7900gs "asustop" with 1,2 ns mems ... whatever which kind.
My target was 700 on core , but it seems to be no so in' easy, maybe even
unpossible
Core is unstable on 670 mhz even @ 1,55 v [checked] , a there is no visible diferences betveen 1,4 and 1,55 v [670mhz is last stable config every time]

I should mention that all "chips" on the back side of pcb are properly cooled by bga radatiors

Core and mems are cooled by zalmam VF700-Cu , and Arctic silver 5 grease. max core temp is under 70C ...

Maybe some chips on the front side should be cooled ? i got some radiators avaible , but im not sure which could be taped

any ideas ? or my 7900 core is over @ 670 ?

[K404]

Might well be temps. Can you get access to a waterloop or a chiller?

[ziddey]

dnarts, are you able to verify that the voltage is indeed increasing with each mod you apply?

1.2ns ram means 833mhz. that's faster than the hynix 1.4ns that came in most other boards.

indeed, how do your temps look. have you tried reapplying thermal compound and remounting?

[dnarts]

Might well be temps. Can you get access to a waterloop or a chiller?

Negative. Only some some fans ,

dnarts, are you able to verify that the voltage is indeed increasing with each mod you apply?
1.2ns ram means 833mhz. that's faster than the hynix 1.4ns that came in most other boards.

If after whole mod its 1,55 [verified] , I'ts quite possible that voltage is indeed increasing in each mod.
True , I'll downclock them to optimal rates afterall

indeed, how do your temps look. have you tried reapplying thermal compound and remounting?

Affirmitive. Already reapllied . I also reapllied conductive inc yesterday once again to make sure.

My temps seems good too : about 67 C on load , other components are warm , but not hot , as I mentioned , I've applied some bga radiators on them ...

Nominal voltage on core is about 1,54 - 1,55 v

edit : i didn't do nothing to cool front side of PCB , maybe some suggestions about it [of course there are radiotors on mems]

[ziddey]

680 is pretty respectable as it is already. I'd probably stay on 1.45v, especially with the vf700cu. 67'c isn't bad at all, but compared to water where I never see about mid 40's under load, it's still pretty hot.

when I was on vf900cu, I was also below 50'c with 1.5v. i apologize for not having much experience with those temps and the voltages to know if it's a problem or not. i did run 1.4v with stock cooler and had temps in the 80's. my o/c was around 650 or so iirc.

i'd probably stick with the 680 core and fiddle with geometric deltas. maybe you could squeeze a little more performance from there.

[dnarts]

680 is pretty respectable as it is already. I'd probably stay on 1.45v,

maybe you are right , but 700 is so nice piece of number

i'd probably stick with the 680 core and fiddle with geometric deltas. maybe you could squeeze a little more performance from there.

what geo delta are u using ?

[KoolDrew]

What would you recommend the max voltage be for a 7900GS cooled by a V-1 Ultra? Also, where could I get conductive ink? When shadding with the pencil, you just shade it until both sides are connected?

Looks like I should go out and buy a multimeter too.