Mixing cards in sli

[danno1977]

help I have a galaxy geforce 9800gt 512mb it can run in 3 way sli ,its not the low power version and has the purple plastic cover over the fan and heatsink about the same size as the card.can I run this card with an Asus version en9800gt 512mb in dual sli,would it make a difference if the asus card were a low power version .please help

 

[Maziar]

Well you can SLI them but if the ASUS one a low power version,then since it has lower clocks,the Galaxy version will reduce its clock and speed to reach the ASUS model(generally) but if the ASUS one is a normal 9800GT then both will performs on their normal speed.
More in the FAQ:
http://www.tomshardware.com/forum/page-245454_33_650.html
"Do the cards have to be same model?
For "Most" Nvidia cards the answer is yes,but there are some exceptions too like pairing a GTS 250 with a 9800GTX+,which can be done since the
GTS 250 is actually a re-badged 9800GTX+ but again there are some cards like 9800GT and 8800GT which have the same specifications but in general you can't pair them in SLI,some users have reported that by flashing a 8800GT's BIOS to a 9800GT's BIOS,you can do it,but its risky and not recommended.
I wrote about the cards which have different names but can be used in SLI mode in the "Model's section" down this post,other than those all other cards must be same model in order to run in SLI mode.
but about AMD/ATI models,for models like X1900 series and lower you have to use the same/master card to use CrossFire but for HD 2xxx series and up,check the compatibility chart on top of this post.
For Nvidia cards,here is an example:
You have a NVIDIA Geforce 7800GTX 256, and you want to add another card , the second card has to be 7800GTX exactly.

But what about the memory? Can you add a 7800GTX 512 and use that with 7800GTX 256?
It's recommended to use a 7800GTX 256 with a 7800GTX 256 and 7800GTX 512 with 7800GTX 512.
However you can use a 7800GTX 256 with 7800GTX 512 , BUT the 7800GTX 512 will lower its RAM to 256MB to operate with the other card, so it wont have its true power. (This option isn't recommended. )


What about brands ?
Well the brand doesnt matter , again for example , you can use a XFX card with a EVGA card , or a SAPPHIRE card with a DIAMOND card , just make sure they have the same memory and same clocks.

What will happend if 2 cards have the same amount of memory but one has higher clocks than the other?
One of the best ways to learn is to make examples.
You have a 8800GT(Normal edition,no OverClocks) and you want to add another 8800GT(Which is OverClocked),then:

1_The OverClocked one will lower its clocks to reach the Non-OverClocked card.

2_You can OverClock your card(The one that has Stock frequencies) and reach the OverClocked card.
Remember, you cant ALWAYS OverClock the normal card to reach the other card,because it may not OverClock that much and may become unstable.

WARNING:There are many exceptions in Computer Hardware, for example "Mousemonkey" (a trusted member in this forum) has told me that when he puts his ASUS 7900GT card (Which is at stock speeds) with a XFX 7900GT(A OverClocked card) the ASUS one raise its clock to reach the XFX one which is an exception and there are lots of exceptions in Computer Hardware."

 

[danno1977]

thankyou very much,actually just bought 2x gts250 for a steal,a few other people said that it may work or may not,werent really committed to say either way,thought it would easier just to upgrade to something a bit newer

 

[danno1977]

Best answer selected by danno1977.