Unorthodox ram sizes and bit interfaces on GeForces?

<jimmy.desiderio.RemoveThis@gmail.com> wrote in message
news:1192047091.411092.215340@o80g2000hse.googlegroups.com...
> Is having 640mb and 768mb of RAM a bit off for a graphics card? I've
> always known them to go from 256mb, 512mb to 1024mb like ATI cards.
> Clearly Nvidia is the best card, but why the different ram sizes?

Someone at Nvidia did some tradeoff analysis and figured 1024 MB is too
much, yet 512 MB is not enough.

> Also, the bit size too. It's 384-bit compared to the 512-bit ATI.
> But they went from 256-bit.

Someone at Nvidia did some tradeoff analysis and figured 512-bit is too
much, yet 256-bit is not enough.

> I'm just curious as to why Nvidia is raising their bit interfaces and
> ram sizes this way.

Why is AMD going with triple-core CPUs? Why do hotdog weiners come in packs
of 10 but buns come in packs of 8? (Though I suppose no one can top
Nintendo, selling overpriced controller gloves in packs of 3...)

--
"War is the continuation of politics by other means.
It can therefore be said that politics is war without
bloodshed while war is politics with bloodshed."
 >> Stay informed about: Unorthodox ram sizes and bit interfaces on GeForces? 

jimmy.desiderio.RemoveThis@gmail.com wrote:
> Is having 640mb and 768mb of RAM a bit off for a graphics card? I've
> always known them to go from 256mb, 512mb to 1024mb like ATI cards.
> Clearly Nvidia is the best card, but why the different ram sizes?
> Also, the bit size too. It's 384-bit compared to the 512-bit ATI.
> But they went from 256-bit.
>
> I'm just curious as to why Nvidia is raising their bit interfaces and
> ram sizes this way.
>

Looking at the back of a video card can explain a few things (but not much).

EVGA 768-P2-N831-AR GeForce 8800GTX 768MB 384-bit GDDR
http://images10.newegg.com/NeweggImage/productimage/14-130-072-14.jpg

There are twelve "sites" replicated on the back of the video card.
Three sides of the GPU, appears to interface to four chips.
A picture of the bare card, front view, could confirm that.

384-bit divided by 12 equals 32 bits wide per chip. Hey, that is a
nice power-of-two number, so no one can be upset about that.

768MB total memory divided by 12 equals 64MB per chips. Again,
no one can complain about that not being a nice power-of-two number.

So if you count the number of memory chips, and do a few divisions,
it all works out in some way.

The wider you make the memory, the more potential memory bandwidth.
Make it a little wider, and you can offer a few more gigabytes/sec than
the competition. Almost like mammoth TV sets, where one company makes
a 107" TV, so the other company makes a 108" TV, then goes to a trade
show and puts a card on top of it that reads "World's Biggest". Until
the next trade show...

Paul
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