5 Ways for a Better 6800 GT Overclock

[HaLDoL]

I’ve been testing my GT a lot lately and was able to achieve a 473Mhz 3dmark2003 run on aircooling (http://service.futuremark.com/compare?2k3=3649129) which seemed pretty high compared to other GT overclocks ( http://www.xtremesystems.org/forums/...ad.php?t=45876 and http://www.xtremesystems.org/forums/...ad.php?t=49832 ). That’s why I wrote down my tweaks below. I hope it helps other GT users.
When I first got the card, it seemed to be an average card, it could do 415Mhz on the core and 1.1Ghz on the mem with stock cooling and voltage. And that was only benchmark stable. For games I had to drop to 400.
The card is a reference design GT with the mermaid on the cooler from Aopen. So, after weeks of tweaking and testing it could do 473Mhz stable enough for 3dmark 2003. As this overclock is achieved without any soldering or resistor pencilling, a lot of people should be able to reach comparable clocks. These tips could also be useful for other Geforce 6x00 cards.
So here we go:

1. Cooling
It’s obvious that if you want to overclock on air you’ll need better cooling, I’ve put a SLK900u AMD heatsink on it and a powerful fan. On previous generations of Geforce cards this was an easy thing to do, because the holes in these cards were large enough to fit 4 long screws. The placement of the holes around the GT core was different and too small for my screws but with some zipties I’ve managed to put the cooler firmly in place. The effect on the temperature was enormous of course. With 20°C ambient, the gpu never went above 40°C stressed. So the cooling was ok. Any cooler with lots of copper should be sufficient (NV5 Silencer for example).

2. Bios
With better cooling the next logical step is raising the gpu voltage from 1.3V to 1.4V, it can be done by flashing a new bios. You can extract your original bios with nvflash and mod it with Nibitor to 1.4V. Set 2D voltage to the same value as your 3D voltage for better stability. 1.5V didn’t help my overclock, but it’s worth trying. Get all the necessary tools, howto’s and biosses at http://www.mvktech.net/ (Mavke’s site).

3. Power
The biggest problem with GT’s is power, ultra’s don’t come with an extra molex for no reason. So how can we stabilize the power supply to the card, even with only one molex?
One option is to use 2 power supplies. The second PSU is only to provide power to the molex of the card. If you don’t want to fry your card, you’ll have to connect the green and the black wires from both PSU’s to make them boot up simultaneously. If you don’t have a clue what I’m talking about, don’t even try it.
A second way for stabilizing the incoming power is described here (thanks to Reject for the crazy idea, but it works): http://www.xtremesystems.org/forums/...ad.php?t=48577 . It gave me some extra 5-10Mhz.
Also, use clean powerlines, with no other peripherals attached. My Antec TC 550W has a molex at the back of the PSU, using this molex gave me the best results.
A serious overclocked A64 system (vcore > 1.75V) could influence your cards overclock (meaning less). I noticed this especially in 3dmark 2001.

4. AGP
Disable fastwrites
Set AGP voltage to 1.8V at least
Set AGP frequency to 81 (use clockgen).
Tested on a DFI S754 nf3 board and it helped me to get those extra Mhz and stability to complete a benchmark.

5. Rivatuner
Use Rivatuner for overclocking, it has 2 very useful options that can be enabled in the power user tab.
- Disable internal clocktest
- Disable any kind of throttling by forcing 3D performance clocks (http://www.vr-zone.com.sg/index.cgi?i=1582&s=3 thanks to Shamino)
Throttling problems are due to power or temperature. Most of the time it’s a power problem. Disabling the throttling mechanism will help finishing that precious benchmark without performance loss. That is, if you’re lucky, most of the time, it will just freeze and give you a corrupt screen. The Rivatuner author warns that disabling throttling can damage your card, so be careful.

That’s it, I hope it can help you reaching that 470+ overclock without any hardmods, it should be possible now if you follow my tips.

If you do want to hardmod your card, look here : http://www.xtremesystems.org/forums/...ad.php?t=48876
The vcore mod (thanks to shamino) : http://www.vr-zone.com.sg/?i=926&s=1
Vmem mod: http://www.vr-zone.com.sg/?i=1622&s=1

If you have comments or other good tips, let me know.

[reject]

wow my mod worked
i think on a dual 12v rail psu the effects would be more evident
on my rivatuner the performance thing is greyed out, i thought it only worked for FX cards.
what bios do u use, i found best results on my stock sparkle

ure scores own me mate good job and nice post

[sky]

this sounds pretty good, have to try it on my gt ...
btw this autooverclocking / detect clocks via the nv-drivers is utter crap. my card usually craps out at ~420 core and when it craps, the mem is only at 1120 or so... and the mem can actually hit 1151 without hickup ... so i don't trust it all that much

[rookiekiller]

hi guys, i cant find disable clock test in riva =o( there ist only bart, krusty, homer and so on... plz help me.

i have gainward power pack 6800gt

[IMG][/IMG]

[reject]

here ya go matey

[HaLDoL]

wow my mod worked
i think on a dual 12v rail psu the effects would be more evident
on my rivatuner the performance thing is greyed out, i thought it only worked for FX cards.
what bios do u use, i found best results on my stock sparkle

ure scores own me mate good job and nice post

Look in the power user tab in rivatuner. You must enable it.
I used the bios that came with the card and modded to 1.4V en 2d=3d

[rookiekiller]

i cant find it =o( theres only name of simpsons...

[Dunk]

Fantastic post.
I'd be tempted but given that I just fried a GT, I'll pass and take what it's going to give me at default volts etc.
My upgrade fund just took a hefty dent

[HaLDoL]

i cant find it =o( theres only name of simpsons...

Try to reinstall, get the latest version at guru3d.com

[Bradbury]

HaLDoL: What do you get in 3d05 with 71.2x drivers?

[HaLDoL]

HaLDoL: What do you get in 3d05 with 71.2x drivers?

Only 6306 with 71.20

Compared to my 66.93 score:



I've discovered that sideband adressing enabled gives you +200 point in 3dmark 05. Unfortunately I already had it on

My GT is sold, I have a BFG 6800u now. Will try to break some records with the ultra.

[sky]

well, i modded my bios to 1.4v and could clock higher ~430 core, 1170 mem, but whenever i tried to run a 3d mark at those settings, i would - sooner or later - get a nice beautifully (?) colored checkerboard. no matter if i used 430/1150 or later on 410/1100 (what i can run for days with the default 1.3v bios). and of course this would lock up immediately .. or well.. i couldn't see much anything else, so i had to reset anyway. cooling wasn't an issue, as i mounted a 6800ultra heatsink, plus two additional fans. one 80mm straight above the aluminium core-cooler (after removing that thin aluminium coverplate) and another 120mm hitting on the 6800gts mosfet sink.

grrr crappola. btw i only upped the 3d voltage, so now i wonder what it is that is causing these checkerboards - even at clocks that work flawless with less juice. anyone got an idea?

/ed. spell-o-holic

[HaLDoL]

well, i modded my bios to 1.4v and could clock higher ~430 core, 1170 mem, but whenever i tried to run a 3d mark at those settings, i would - sooner or letter - get a nice beautifully (?) colored checkerboard. no matter if i used 430/1150 or later on 410/1100 (what i can run for days with the default 1.3v bios). and of course this would lock up immediately .. or well.. i couldn't see much anything else, so i had to reset anyway. cooling wasn't an issue, as i mounted a 6800ultra heatsink, plus two additional fans. one 80mm straight above the aluminium core-cooler (after removing that thin aluminium coverplate) and another 120mm hitting on the 6800gts mosfet sink.

grrr crappola. btw i only upped the 3d voltage, so now i wonder what it is that is causing these checkerboards - even at clocks that work flawless with less juice. anyone got an idea?

Checkerboard crashes are due to power instability. Did you do what I described under power and agp? They may seem trivial, but they do help. Raise agp voltage/ frequency, disable fast-writes, make a double molex, etc... Test on a non-overclocked cpu first.

[[XC] moddolicous]

I dont mind modding a bios for you if you need the 1.4V/ 1.5V bios. Just shoot me a pm with card make and anything else important.

[Playful_Buffalo]

bookmarked

i am gonna try some of these mods

[sky]

Only 6306 with 71.20

Compared to my 66.93 score:



I've discovered that sideband adressing enabled gives you +200 point in 3dmark 05. Unfortunately I already had it on

My GT is sold, I have a BFG 6800u now. Will try to break some records with the ultra.

erm, ONLY 6306 with the 71.20's? what was the best driver regarding scores for you? i'm still running 66.81's as they gave me the most. but then again i didn't test them all. nv just has too many drivers to keep track of

[HaLDoL]

I've only tested 66.93 and 71.20 unfortunately.

[HiJon89]

From what I've seen, any of the 71.2X's are good. I would just go with the 71.20's the 71.24 and 71.25 seems to just fix SLI problems.

[don_vercetti]

just out of interest, how come raising the AGP freq. helps overclocking the GPU? ala point 4.

[uclajd]

I'd put power 1(b).

The 6800GT is a power hog when overclocked.

It also runs hot[ly] as hell, which is why H20 is so helpful to this particular card and why cooling is 1(a). I went from like 80C to 45C under load with water. I've never seen a CPU even come close to that kind of drop under water. Then again, CPUs don't ship with the woefully inadequate cooling that the 6800 series does.

One thing is clear: If you have crappy power, you'll be very hard-pressed to have successful OCs with a 6800 series card. Now that I have my Powerstream 600 I should slip the 6800 GT back in and see how it goes. Mine would autodetect really high, but crap out under load, which was power starvation.

[revenant]

I know this is an OLDish thread... but I am having some issues OCing my MSI GTs in SLi... I think it's a power issue from my mobo not getting enough juice through the pci-e slots... I have an MSI k8n nei4 plat sli with a two NX6800GT's and a SilverStone Zeus psu... those cards have that nice copper cooler in them... I have put AS5 over the GPU, I have a 120mm fan right on the cards, plus a vantec fan card under the bottom card... they are stable at 375/1070 but not much higher than that...

does anyone know if it's possible to increase the pci-e voltage on a neo4? I am running the 5 beta 6 bios.

[neoman]

nice tweaks m8 i will try those cheers

[HaLDoL]

I've given credits where needed. I'll be the first to admit if any of those tweaks weren't mine. I don't read overclockers.com, so I don't know if those tweaks were posted there.

1.4V is perfectly safe, my GT runs 6 months @ 1.4V and no problems. This is xtremesystems.org after all, and not I-am-afraid-I-will-kill-my-card-if-I-increase-the-voltage.org. Then this is not the site for you.

[FireDragon]

here ya go matey

Hey man are you using lightstep if so how do you like it?

Dragon

[FireDragon]

Also what about flashing to an Ultra bios if you card can do those speeds i have heard that if it can that it can also ne you a little better clocks and some better performance...

Dragon