Im pretty shure i know what your talking about ...I just dont know how to explain A better example about what im talking about..

Example:If i were too..

SLI two GTS512mb's or even GTS1big's you will only get 512mb(57.7) of bandwidth because of 256bit controler and SLI...It defaults to ONE cards memory for both cards regardless...Fact


I dont think this is the case with the 3870x2... Crossfire( I may be wrong) uses all the vram on the x2. unlike SLI. Both cores do not have to share 512mb....Each core uses its own 512mb...GPU1 uses 512mb and GPU2 uses the other 512mb. Both GPU's dont use the same 512mb shared like the GTS in SLI.


This means means the 3870x2 2x256bit should have 57.7 per 512mb..Per GPU..?

3870x2 GPU's use a total of 1gig with (2x256bit controlers )this means 512mb for each core...I Know that i said there is a total of 114gb/s when in crossfire mode at 100% This will hold true if the card uses all 1gig..Im trying to find this out..Ive always thought Unlike the GTS in SLI the 3870x2 uses a seperate 512mb for each GPU .Each GPU always has 512mb at hand...This is where Nvidia would lack in SLI. You can (Only use the Memory from ONE GTS/card) for both Cards/GPU's in SLI .You will not be able to use the Vram on the secondary card..Which means you will only have 57.7 for both GTS cards!...

Well Bandwidth wise Nvidia's Ultra which has 106Gb/s with 768mb would be higher if it had 1gig..On second thought if the 3870x2 used 512mb for Both GPU's =28.8gb/s there is no way it could Run HIGH res and beat the GTX/Ultra . I know GTS 256bit bus can push 1gig but at 57.7. With that inmind the 3870x2 would have to run 512mb per core or all 1gig is combined on one 256bit contoler somehow..It has 2x256bit though!

I really hope im wrong,But i know for fact 2 GTS512mb total in SLI only use 512mb, despite there being 1gig total between two cards..I pretty shure that Crossfire will use the Vram that is on its own card for its own GPU.Crossfire alternates between both cards using the Vram dedicated for each GPU.

Yes we all know GPU-Z is suppose to read 57.7 for each GPU when selected on the 3870x2....Ive been searching for the Info on 3870x2 Crossfire and 1gig vram . I cant believe No one has even brought this point up before..

All ive found is that SLI/CROSSFIRE uses the max Vram of the highest card...
What bugs me is the 3870x2 is ONE CARD with 1gig of ram and 2x256bit controlers.I really need to know if this single card uses the Max ram(all of it) Or only half of it..On a side note Even a GT/GTS with 1gig runs at 57gb/s with a 256bit bus/controler. Rember There are (two 256bit buses on 3870x2) Each GPU' uses thier own 256bit and 512mb ,57.gb/s for each core instead of both using the same 256bit controler...I cant find any documentation that says the 3870x2 only uses 512mb of its 1gig for Crossfire..

It wouldnt make sense to have 1gig on a 3870x2 if you only use 512mb and one 256bit controler to get only 57GB/s now would it.

Thanks