8800GTS (640) with 8800GTS (320) "SLI" - Maybe?

[Morbid666]

I've been quite curious about this subject for a while now:

As far as i know, SLI will only work with identical chipsets - well in that case it should work with 8800 GTS 640MB & 320MB models, right? I wanted to find out whether anybody tried this setting or maybe how they worked together in SLI...

I've bought ASUS 8800 GTS (640MB) as soon as it came out and been happy with it ever since - very nice improvement from what i had (ASUS 6600GT Silencer). I would consider myself a heavy gamer, so now I'm looking forward in going SLI as games improve (Colin's DIRT).

Can anybody advise me about this please - I couldnot find anything regarding to this online. Othervise I would have to go for 640MB option which is quite expensive for me still, second time around.

Also I'm concerned about the wattage... Would 520W PSU be enough for SLI? - I have 3 Hard Drives (with Hard Drive fans each) & 3 Case fans.

I use RivaTuner:
550/880
AA-4
AF-4
1280x1024 LCD

- THANK YOU!!!

 

[MarcVenice]

It would work, but you would only have 320mb instead of 640, making it a REALLY expensive 8800gts 320mb And the wattage might not be the problem, the amps your 12 rail(s) put out might be though. I think you need 30a combined at the very least for sli-ed 8800's.

 

[Morbid666]

Thanks MarcVenice!

- you saying that the total amount of memory wouldn't combine?
so 320&320 would give 640MB of texture memory and 320&640 would still give 640MB in texture memory as only one half of 640MB card's memory is used - right? going SLI with both 640MB cards is the only "sober" solution then?

- and do you know how do i calculate the MAX wattage my hardware would drain from PSU with this setup?

 

[MarcVenice]

theres some PSU calculators, look one up on the psu forum or google for one, it should come up pretty fast.

And no, 320 + 320mb wouldn't combine, you would be stuck with 320mb TOTAL! So yes the only real sober thing to do is getting another 640mb 8800gts. At the resolutions you play it you barely need more then 320mb though, so it's up to you. Perhaps sell the 640mb version, and buy a gtx or whatever. But do you really need sli-ed 8800's ? I mean, Dirt runs pretty good on my PC with my 8800gts 320mb. Don't put everything on ultra though, it barely improves IQ but will make things slow as hell.

 

[Morbid666]

Thanks!!!

 

[TheRyuu]

Can you really SLI a 640 GTS with a 320GTS?

I thought the cards had to be the same (except for the manufacturer).
And IMO, an overclocked 8800GTS is fine. I suggest you not go to SLI.

Keep the single card unless your gaming at some insanely high res. Then you could go SLI with another 640 GTS.

 

[n7]

MarcVenice, have you tested this?

How are you certain this is going to work?

 

[MarcVenice]

Haven't tested it myself. http://www.slizone.com/object/slizone_ask_mmm013.html mentions the following though:

"If you feel you need 256MB or even 512MB of graphics memory for certain games, then you need to make sure that each card has that much memory. Also keep in mind that if you mix a 128MB GeForce 6600GT with a 256MB GeForce 6600GT that BOTH cards will operate with 128MB of graphics memory (the lowest common memory size of the two cards)."

It comes down to the fact that you need 2 identical gpu's, which the 8800gts 320mb and the 8800gts 640mb have, if you want to run the cards in SLI. I'm simply assuming the same fly's for 8800's, but I have seen it mentioned on the forums before, so there's no reason not to.

 

[firewolfsm]

Remember that if you do this, you'll only have 320MB TOTAL, SLi mirrors memory, it doesn't add it up.

You'll actually have less VRAM available than without the second card and some games might just run slower.

 

[MarcVenice]

I allready said that And it's because of the way games run and how SLI works. 1 card will do frame #1, and the second card will render frame #2. If you think about it like that, it makes sense that only the least amount of memory gets used.

 

[Morbid666]

Just checked the power consumption from my hardware at "http://www.extreme.outervision.../psucalculatorlite.jsp" - very nice PSU calculator. Apparently my lovely rig is loading my system at 85% of my PSU total power (520W) when working at its maximum, so if i add another card in - i will have to get another PSU too (extra 100 pounds). Its 350 ($700) for a small performance gain. /// ohh...

... anybody knows when "9 series" coming out???

 

[MarcVenice]

Tbh, thats an overestimation, worst case scenario. But with 28a on your 12v rail two 8800's might be a little to much.