8800 why 768mb??

[ichabod crane]

anyone know why the new nvidia cards have only got 768mb of ram on them? i would have thought they should have 1024 on,but it would seem they have just stuck an extra 256 onto the 7950gx cards

 

[Rroff]

Its because they have 2 different areas of memory... its not like the traditional one stack of 768Mb, but one pool of 512 and one of 256.

EDIT info may be wrong - was what was reported in early briefs on the 8800

 

[Zefan]

Mosy likely is the result of R&D realising that the generation of games the 8800's are aimed at will only need 768mb.

 

[The Running Man]

cost/benefit analysis

who can say what it "should" or "shouldnt" have?

 

[Stephen B]

CYNICAL MODE ON............

marketing stategy so that you run out and buy the 1 gig one in a few weeks

CYNICAL MODE ON STANDBY

 

[Jabbs]

I thought it was to do with it having a 384bit memory interface thus 768ram and the gts having 320bit memory interface and again having 640meg ram.

 

[roadie]

I thought it was to do with it having a 384bit memory interface thus 768ram and the gts having 320bit memory interface and again having 640meg ram.

Yes. Unlike the previous posters, this is the correct reason. Both the GTX and the GTS have the same memory density but the GTS is missing two RAM chips. Obviously the bus to these chips is not being used.

 

[The Running Man]

okay then, so why did they chose the 384bit memory interface knowing it would put them at 768MB? they could have gone for more, and made it a gig?

 

[roadie]

okay then, so why did they chose the 384bit memory interface knowing it would put them at 768MB? they could have gone for more, and made it a gig?

Wow, does that open a can of worms! If they went for a gig of memory then it appears like they would have, like ATI seem to have done, gone for a 512 bit memory bus. Given the number of transistors the 8800 already has, its power consumption, cost, and already exceptional and balanced performance, then this is something it doesn't need.

 

[Cyber-Mav]

I thought it was to do with it having a 384bit memory interface thus 768ram and the gts having 320bit memory interface and again having 640meg ram.

you are correct

 

[Cyber-Mav]

okay then, so why did they chose the 384bit memory interface knowing it would put them at 768MB? they could have gone for more, and made it a gig?

board complexity and costs also step in here. its not easy to just bump up the memory interface bit size. if it was then even the older generation of cards would have been using 512bit interface.

 

[titaniumx3]

Yep, and if you read some of the early descriptions of the R600 (which will have a 512bit memory interface) its PCB is supposedly thicker than previous cards due to this increased 'complexity'.

 

[Sir Random]

Another reason for going with 768Mb is lack of space on the card. The 8800 gpu is quite large, and all 12 64Mb ram chips need to be equidistant from the gpu (all traces should be the same length).

You can see from the pic that the 12 chips are spaced equally around the gpu, but to fit an extra 4 chips, they'd need to make the card much taller and put the chips at the bottom (between the gpu and the PCI-E connector), or rearrange the layout completely.

 

[Cyber-Mav]

if they scooch the existing memory chips closer together then they can fit the extra ram on easily.