overclocking 7800 gt sli's

arciced

Member
Nov 21, 2006
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hi, I have two xfx 7800 gt cards in sli. when I had 1 card I was able to over clock it to about 495 core, and showed considerable fps improvement in games. now that I added a second card I am not able to over clock correctly. If I move the core clock from 450 to 475 for instance the game will not show one extra fps, and when I exit the game the computer crashes, or the computer crashes while playing after 10 mins.

I have the impression I am only over clocking one card and not both, is there a way I can select each individual card to over clock?i have rivatuner 16.1 and coolbits 2. in riva tuner i turned on the extra pixel and vertex options but not one fps was gained. thanks for any help, i cant play neverwinter nights more than 15 fps =\.

drivers: 93.71

asus-sli premium
3800 x2
2 gig ddr
 

josh6079

Diamond Member
Mar 17, 2006
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It's been about a year since I had my 7800GT SLI @ 550/1300 setup, but I'll try to walk you through what I remember.

Try aiming for a 27 MHz jump instead of 25. I remember that every 27 MHz increase on the core proved to give a noticeable performance improvement.

Also, I was never sure whether or not I could overclock both cores while having them in SLI, so, what I did was bios flash both to the modded 1.5V bios from mvktech.com and adjust both cards to the same specs individually.

I don't remember which rivatuner I used, but I think I ended up just sticking with coolbits.

What are your temps like?
 

arciced

Member
Nov 21, 2006
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hmm this bios stuff interests me.. theres nothing about it on the xfx site.. on your link i got the nvflash 5.38 and XFX.7800GT.PCIe.256MB.Rev.01.rom. i have not went into dos to upgrade it yet..

first i want to know how can i find my current firmware version

second, do i have to plug in each card seperately to upgrade them independently?
 

arciced

Member
Nov 21, 2006
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ok, both cards were up to date with the firmware. they both had 05.70.02.13.12 which is the same version as the rom i downloaded..

overclocking in any interval does no help, just crashes
 

CKXP

Senior member
Nov 20, 2005
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what about your PSU(brand/make)? maybe it can't handle the extra load of a second 7800GT
 

TheRyuu

Diamond Member
Dec 3, 2005
5,479
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Use Rivatuner since coolbits is pretty much broken in the 93.71 release.

Also, XTreme-G FTW!
http://www.tweaksrus.com/index.php?opti...an&task=doc_details&gid=778&Itemid=41/

Anyway, with Rivatuner first thing you can do (if you know what your doing) is disable the "test clocks" thing. It's under power user somewhere so just look. Also, enable Low Power 3d control too, also under power user tab (also, set value to 1, not just click it off).

With that out of the way, use Rivatuner and OC it to the max clocks that you can get. PSU might not be able to handle the second vid card but also the second video card just may no OC as well as the first one did (OC's always seem to decrease when you use SLI them, twice as many thing can go wrong)

Well, if ANY OC crashes then I guess don't OC for now? :p (but what fun is that :))
I guess, PSU is the next thing I'd check. Along with the proper settings in the bios of the motherboard (like is it set to run SLI, is the Peg Link Mode (Asus's automatic OCing feature) DISABLED. That thing caused artifacting on my cards, even on normal. Not sure if your mobo has it though.
 

arciced

Member
Nov 21, 2006
43
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thanks for the replies. so far no luck.
my psu = OCZ GameXStream OCZ700GXSSLI ATX12V 700W

i managed to find the allow low power 3d and clocked that and high power up to 495 core but to no avail. i couldnt find how to turn of the test clocks. yet to say again, whenever i overclock a single card i would get about 15% performance increase. well my benchmark would have put me right between GT and GTX speed. most games would gain on acerage 8FPs which went from 25fps to over 30 in most cases which makes alll the difference. if /I could of gotton 15fps increase by overclosing sli I could play smoothly in best visual effects

but now with sli clocked at 495 my bechmark is the same as it would be if i left it at 450.. hasn't BSOD yet though odly.. when i spent all my saved money for this second GT card I was expecting to over clock it to get it between GT sli and GTX sli but i will just have to sulk, and wait 6 months before i can afford 8800, and play my newr games neverwinter nights 2, nfs carbon in lesser quality.. if i wanted lesser quality i woulda went with xbox 360 instead lol.. sigh
 

arciced

Member
Nov 21, 2006
43
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yo guys this thing is weird. why is it when i move the core clock from 450mhz to 650mhz the test doesnt fail? i can enter a game with no fps change.. its as if the settings hgave absolutly no effect
 

arciced

Member
Nov 21, 2006
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it turned out that the second card i bought, used from ebay, was a bad card. even though it was the same modal number as the first card i bought new, this ebay card could not be over clocked. in fact i have just tried it all by its self and any clock speed test including default fails.. so i assume this is why i had all these problems when i went to over clock them together, the setting accepted for some reason because the first did but since the second would not work faster they were running out of sync.. also another funny note, this ebay card got 18fps in a game the first card got 32fps in. so i am surprised that i saw the performance increase that i did when adding this defective card to my good one. most games played with a good 30% fps increase, only a few games like far cry played really crappy like it would go from 50fps to 70 fps yet the smoothness would be very rough, not bad fps rough but something else.. im sure that dick face who sold me that card on ebay for $250 is just laughing that he got so much for it after he probably burnt it by over clocking it too much although i didnt know you can hurt them by doing that or perhaps the fan went bad and it bernt i wouldnt be surprised because the fan on the ebay one was much more noisey than the first card so he could of replaced it with something crappy..

anyways i sold the good one for a hundred, and gave the bad one to a friend who wont know any better.. then got myself a ati x1950 pro that has a near x1950 xt clock speed for only $200. the card runs better than my previous 7800 gt sli, and it is whisper quiet. its an IceQ3 modal and i recommend poor ppl to get one instead of the more expensive ones.. you can even crossfire it but i dont have the $ for another nor do i need another because this single one plays all the games fine. like it plays splinter cell double agent with everything at the highest, except shadows need to be turned off, and it very rarly dips below 30, but sometimes in low 20s when looking at the ground.. and rainbow six vegas runs in 30's 40's most of the time with full gfx quality in 1024x768 but as long as shadows are turned off.. shadows are a funny thing because when i compare what the game looks like between shadows fully on and with them off you arnt really missing much of the experience yet they can bring 40fps to 10fps quiet easy and its like that in every new game i play such as neverwinter nights 2 was unplayable until i decided heck ill just turn off shadows and guess what i couldnt even tell they were off because they dont appeal to me

case closed, screw ebay 4 ever