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View Full Version : SLI w/ a 256MB and 512MB 7800GTX?


Clay
12-05-05, 08:52 PM
I'm trying to get the following two cards to work in SLI:

BFG 7800 GTX OC 256MB (http://www.nvnews.net/reviews/bfg_geforce_7800_gtx_oc/index.shtml)

MSI NX7800GTX-VT2D512E (http://www.msi.com.tw/program/products/vga/vga/pro_vga_detail.php?UID=708)

The first thing I did tonight before starting to get this to work was to run DriverCleaner. I cleaned the driver.cab and XPSP2.cab files first. Cleaned the NVIDIA drivers with it, rebooted into safe mode first, etc, etc.

Then, I installed the 6.70 nForce drivers (nForce4_amd_6.70_winxp2k_english.exe)...rebooted. ..then installed the 81.95 drivers (81.95_forceware_winxp2k_english_whql.exe)... rebooted.

Even though you're supposedly able to run two different memory sized cards in SLI (see italicized paragraph on the bottom of this page (http://www.slizone.com/object/slizone2_rel80.html)) I'd had no luck. So, I decided to flash the BFG 256MB card with the more recent BIOS from the MSI 512MB card...

Once I confirmed that the system was stable with the BFG 256MB card, I used NVFlash 5.25 and made a backup of my 256MB card's BIOS (version 5.70.02.11.25).

Then, I shutdown, removed the 256MB card and installed just the 512MB card.

Then, I made a backup of the 512MB card's BIOS (version 5.70.02.25.02).

Then, I shutdown, removed the 512MB card and installed the 256MB card again.

Finally, I tried to update the 256MB card with the 512MB card's BIOS...I received this message:

http://tinypic.com/i431xx.jpg


After no success flashing, I tried to set the Coolbits value to 18 as was instructed from slizone.com:

http://tinypic.com/i6ms07.jpg



No luck. I tried setting the value to 18 as both decimal and hex. I also tried 1A and some other values that nVTweak sets. Still no luck. All I ever get with both cards installed is this:

http://tinypic.com/i6mst0.jpg

Any ideas?

MUYA
12-05-05, 08:54 PM
Does SLI work with non matched Memory sized cards? I thoiught that was ATi specific (ie crossfire feature?)

Clay
12-05-05, 08:58 PM
Read the bottom of this page. ;)
http://www.slizone.com/object/slizone2_rel80.html

jAkUp
12-05-05, 09:03 PM
I don't think it will work... the GPU's are not similar enough.

Also, trying to flash the 256MB version with the 512MB, even if it work, could damage the card.

In addition to the vast differences in clockspeeds, the 7800GTX 512MB is 1.45v, and the 256MB is 1.4v.

I believe there is a switch to force the flash, but I don't recommend it.

Clay
12-05-05, 09:05 PM
I don't think it will work... the GPU's are not similar enough.I wondered about that but I'm trying to be optimistic (or hard-headed). :)

MUYA
12-05-05, 09:19 PM
Read the bottom of this page. ;)
http://www.slizone.com/object/slizone2_rel80.html
aha! i stand correct but Jakup maybe right, the drivers might be treating the GPUs as different. That is not supported by nv drivers right?

Clay
12-05-05, 09:25 PM
aha! i stand correct but Jakup maybe right, the drivers might be treating the GPUs as different. That is not supported by nv drivers right?Yes. It was worth a shot. I was just curious to see if I could get it to work. Once I saw that message when I attempted the flash I figured that it would be a no-go. I just received word from NVIDIA confirming that what I'm trying to do will not be possible.

superklye
12-05-05, 09:29 PM
*cue all the ATI people to come in and start going on and on about how xfire lets you do this*

:rolleyes2

Clay
12-05-05, 09:32 PM
*cue all the ATI people to come in and start going on and on about how xfire lets you do this*

:rolleyes2If they do then they don't have much sense. :D This was just something I wanted to try to do. To quote a knowledgeable source:

Honestly is doesn't make any sense to buy this combination anyway since you will end up with a 256MB frame buffer for both cards (256MB of wasted memory on the 512 card...and that is expensive!!). :)

MikeC
12-05-05, 09:34 PM
My ATI X1800XT smells weird. :o I can't imagine what 2 would smell like.

superklye
12-05-05, 09:34 PM
If they do then they don't have much sense. :D This was just something I wanted to try to do. To quote a knowledgeable source:

Honestly is doesn't make any sense to buy this combination anyway since you will end up with a 256MB frame buffer for both cards (256MB of wasted memory on the 512 card...and that is expensive!!). :)
Yeah...I never understood how that would be a "feature" on xfire. I mean, I guess if you have an older card and only had money for one new card at the time it would be okay, but I'd rather sell the old one and just use the single new card until I got a matching one instead of crippling the new card.

Clay
12-05-05, 09:43 PM
Yeah...I never understood how that would be a "feature" on xfire. I mean, I guess if you have an older card and only had money for one new card at the time it would be okay, but I'd rather sell the old one and just use the single new card until I got a matching one instead of crippling the new card.
Right, kind of like putting a pair of Enkei ZR-1 rims on a car with a pair of cheap steel rims. :D

superklye
12-05-05, 09:44 PM
Right, kind of like putting a pair of Enkei ZR-1 rims on a car with a pair of cheap steel rims. :D
Yes! That's the exact comparison I was looking for. :p

superklye
12-05-05, 09:45 PM
My ATI X1800XT smells weird. :o I can't imagine what 2 would smell like.
hahahaha! I just saw this now. :rofl

I cracked my back from laughing so hard...ow!

Clay
12-05-05, 09:46 PM
Yes! That's the exact comparison I was looking for. :pOh oh! Or like putting a gigantic fin on a Honda Civic! Well, that's not really an accurate analogy but it sucks too. (rudolf)

TierMann
12-05-05, 10:17 PM
You could try modding an older driver inf before GTX 512 was supported to support the 512. That would report it as a just a G70 from the driver and panel itself. The drivers would have to have mixed vendor support but it might work. I think there's like 2 or 3 candidates in the 81.xx sets.

Riptide and I tried 78.03's with a modded inf and it just showed as a G70 and ran fine. The clocks were reported wrong so couldn't OC, but worked. That's about all the info I have on that and what I'm basing this on.

Here's the question though.. Who knows which version the mixed vendor support was added and which version 7800GTX 512 was added? I could start modding infs if you want to be a lab rat.

jAkUp
12-05-05, 10:23 PM
Oh oh! Or like putting a gigantic fin on a Honda Civic! Well, that's not really an accurate analogy but it sucks too. (rudolf)

I think the absolute worst is Spinner HUBCAPS.

I'm not talking real spinners, I'm talking the $20 hubcaps that they sell at Pepboys... ugh

superklye
12-05-05, 10:26 PM
Oh oh! Or like putting a gigantic fin on a Honda Civic! Well, that's not really an accurate analogy but it sucks too. (rudolf)
hahaha. oh man, crappy analogies crack me up.

zoomy942
12-05-05, 11:19 PM
please choose from the following options...:)

a - its like those cars with fancy tires on the BACK tires, when its a rear wheel drive car

b - nice rims on a car with rear drum brakes.. just look silly:)