7800GTX overclocks with Volt Mods??

[ViperJohn]

NOPE I SOLD IT FOR PARTS

Damn I did not see this soon enough. The card was probably repairable. When the pot came off (and if installed correctly you can adjust them with the card running all day long) one of the traces in the feedback loop opened up. When the regulator sensed no or extremely low voltage present at the feedback pin (VSENP) the regulator would have down one of two things both of which would have shut the Vcore PS down almost instantly as a protective measure.

Viper

[revenant]

ok - VJ - sorry for my ignorance, and thanks for the correction... about adjusting the pot while the card is on.. I need to shut the hell up until I get more in the know here.

[ViperJohn]

ok - VJ - sorry for my ignorance, and thanks for the correction... about adjusting the pot while the card is on.. I need to shut the hell up until I get more in the know here.

You are not ignorant and there is nothing to be sorry about. All I was saying, admittedly in a rushed and not so tactful manner, is if the trimmer is applied to the card properly using the right materials it won't come loose during normal adjusting with reasonable care.

1/16" 3M double sided foam tape work well on a clean surface. Of course you can shear the pot off the card if enough side ways pressure is applied but that applies to soldered on SMD's too lol. It is just a matter of degree.

Viper

[revenant]

ok - well - I was speaking of something I knew little of... but I see your point completely, the biggest danger of adjusting the pot while the card is on is the possibility if weakening, or cracking the solder connections... so attention to proper mounting of said unit should be taken. there's a nice clean section of PCB on the side of the card facing out by the pci-e power socket. Granted the leads have to be longer, but that looks like a prime piece of real estate for the pot.

EDIT: from the images I see that's a favored spot by many.

[ViperJohn]

ok - well - I was speaking of something I knew little of... but I see your point completely, the biggest danger of adjusting the pot while the card is on is the possibility if weakening, or cracking the solder connections... so attention to proper mounting of said unit should be taken. there's a nice clean section of PCB on the side of the card facing out by the pci-e power socket. Granted the leads have to be longer, but that looks like a prime piece of real estate for the pot.

EDIT: from the images I see that's a favored spot by many.

There are good locations right at the mod points for trim pot mounting using "X" style 90 degree bourns 3296 trimmers that do not need leads at all. The lead that connects to the feedback circuit in nothing more than an antenna smack in the middle of RFI/EMI hell. It picks up noise and injects it straight into the regulators feedback circuit. The longer the lead the more noise pickup up.

Viper

[cadaveca]

Couldn't you shield the wire from this, VJ? Filter out the noise? I guess you'd have to scope it tho, eh?

[revenant]

maybe use tiny ferrite beads on either end of the leads? lol. j/k

[ViperJohn]

Couldn't you shield the wire from this, VJ? Filter out the noise? I guess you'd have to scope it tho, eh?

I suppose so but now you are making things even more complicated. The correct trim pots are ready available on line from several sources so there is no need for leaded trimmers at all. They are harder to do and more prone to failure of one form or another. Snagging the lead and ripping it off the card (along with part of the PWCB trace) is #1.

Viper

[cadaveca]

who cares if it's complicated, as long as it's right. i'm sure i'm not the only one with this sentiment.

[Victorshen]

i've done the vGPU and vdd mod today
seems work fine
the default vGPU and VDD of my 7800GTX is 1.424v and 2.09v
by adding a 500ohm pot set to about 200 ohm, vGPU= 1.475v
by adding a 100kohm pot (96.1k according to MM) vdd=2.16v

btw. anyone know whats the max volt i can use on the ram?

thx
[update] add pic

[cheap]

has anyone modded their 512mb card yet?

[Slipknot]

Hello, sorry for my bad english^^

Is it possible to flash a GTX 512 BIOS onto a "old" GTX 256?!?! AFAIK the 512 board has 1.45V Vcore...

[Dr.Leary]

Hello, sorry for my bad english^^

Is it possible to flash a GTX 512 BIOS onto a "old" GTX 256?!?! AFAIK the 512 board has 1.45V Vcore...

Try this instead! http://www.xtremesystems.org/forums/...ad.php?t=81441

[revenant]

has anyone modded their 512mb card yet?

Yes. and this is a good example of how to vmod leaving the pots at the "point of presence"(if you will), sans long leads. Looks like he did a perfect soldering job to me. very clean.

http://www.xtremesystems.org/forums/...0&postcount=47

from this thread:

http://www.xtremesystems.org/forums/...ad.php?t=80471

Also - Slipknot - I would not do that (flash a 256GTX to the bios of a 512mb unit). Even if nvflash would let you do it, which I doubt it would, the card would not post (especially) because the memory speeds on the 512mb (for the 1.1ns mem) are way too high for the 1.6ns mems on the 256... even with the vmods. that's my $0.02

[Chri$ch]

Hello,

i have one question....

what can i give my 7800GTX 256 for a VGPU and VDD voltage with air cooling (Arctic Cooling NV 5)?

Thanks
Chris

[slimais]

Nothing more to say...
(1.8V on core, 2.3v on Ram)
i will try more when i will be not so lazy like now...

[Slipknot]

>i will try more when i will be not so lazy like now


Ya wanna try more Vcore or more MHz?

[slimais]

under load the card shuts it self off if voltage is more then 1,85V
cpu does not nead more voltage because it runs 3Ghz@1,36V
im just too lazy to take out 1Gb of my ram & do it 1:1

[Slipknot]

>under load the card shuts it self off if voltage is more then 1,85V

Which temps ya got?

[slimais]

under load 30c

[Slipknot]

under load 30c

wow, which cooling system da yo use? i have got 49°C under load, watercooled^^

[slimais]

mine is watercooled too, but the radiator is on windowsill & its cold outside

[Slipknot]

mine is watercooled too, but the radiator is on windowsill & its cold outside

A ok, ya are a cheater :-p, i wanna know what ya system will do at 24/7 :-p, or do ya live on northpole? :-p

[sdat1333]

EDIT: PLS SEE LAST PARAGRAPSH

Yes, Im sorry, Ive read throught the last 6 or so pages of this thread and have decided to post just to make sure all my info is right and ask a few questions.

1) I am going to be on aircooling (modded A64 stock heatsink, its a bigger than what i was using before (old socket A heatsink) which still gets like 45ish load temps at 500/1400. Im also gonna add a shroud system to cool the card with around 54cfm of airflow pushed throught the vreg, mem, and core heatsinks collectively. I should be fine right?

2) As long as I have airflow, the voltage regulator heatsink that comes stock should be fine correct? I dont mind replacing it if need be, i would just like save some money.

3) Any links to the trimmers I need? Any part numbers, etc etc, would be nice. I want to make sure Im doing this right

4) I know to turn the pots to max resistance for lowest volts, but which way ups resistance? clockwise or counterclockwise?

5) http://xtremesystems.org/forums/atta...0&d=1120709495 I see in here, the third leg seems to be cut off. What does that third lead do?


Alrihgt mid typing i just realized a major problem.

I was looking at my card and i noticed that C695 is COMPLETELY GONE. I can tell its been ripped off. But Ive been nothing but carefull around this card, and i cant find it lying aroudn my work area. Will the card work w/o this? Im tyring to figure out what happened, cause if it will work w/o it there than it could have happened a while ago. PLS HELP

[ViperJohn]

Try this instead! http://www.xtremesystems.org/forums/...ad.php?t=81441

That bios is for a 7800GT not a 7800GTX!!!

You can not get more than 1.400 Vcore using firmware with a GTX. The card lacks the hardware to switch the Vcore regulator VID pins to anything higher than 1.400.

Viper