290X VRAM Crossfire

[JeoTek]

If I buy a 390X or 295X2 (each has 8GB of RAM) or an 8GB Sapphire 290X to crossfire with my 4GB ASUS DirectCU OC 290X, will I be able to put the 8GB card i would get into the first PCIE slot to use 8GB of RAM. Or will I be stuck using 4GB of VRAM max because of the 290X?

Basically, will a 4GB card bottleneck the 8GB card, or can I use the first cards 8GB of VRAM?

 

[TheFluffyDog]

Yes, and no? Crossfire needs to Mirror memory for both cards, but I believe only the first card (or the one doing the "displaying") is the one that holds the frame buffer. SO you would be limited to 4GB of Vram for things like textures and such, but you should still benefit from the extra memory for things like frame buffer. However, Frame buffer doesnt use a whole lot anyway, so it would still be a bottle neck overall.

LAstly, you probably dont need more than 4GB of Vram.

And if im wrong about the Frame buffer i hope someone corrects me, i'd ,like to know as much as i could as well.

 

[Gingerbread]

It won't bottleneck it but just as you thought you would be limited to only4gb of VRAM.

 

[maxalge]

If I buy a 390X or 295X2 (each has 8GB of RAM) or an 8GB Sapphire 290X to crossfire with my 4GB ASUS DirectCU OC 290X, will I be able to put the 8GB card i would get into the first PCIE slot to use 8GB of RAM. Or will I be stuck using 4GB of VRAM max because of the 290X?

Basically, will a 4GB card bottleneck the 8GB card, or can I use the first cards 8GB of VRAM?

only 4gb for all three at the moment


such a "three" card setup has diminishing returns, dont expect gains like the one from jumping from 1 to 2 cards

 

[jimmysmitty]

Well you have some wrong infomation. The R9 295x2 is listed as a 8GB VRAM GPU but it has 8GB of VRAM total, 4GB per GPU as it is a dual GPU card. If you bought a R9 295x2 it would be the same as adding in two more R9 290Xs to your system and be limited to a 4GB VRAM frame buffer.

If you bought a R9 390X, I am not even sure if it will Crossfire, or 290X 8GB it would be limited to 4GB total VRAM frame buffer as well.

 

[blazorthon]

The 390/390X and 290/290X/295 are all compatible for Crossfire (even between X and non-X) since Catalyst 15.7. The VRAM will be limited to the lowest card. I'm not aware of any benefit existing from having the primary card having more memory than secondary/tertiary cards.