VRAM and Memory Bus

[sYankOv]

I've always wondered which is better: a 2GB 256 bit or 4GB 128 bit GPU
And please explain why.

 

[ajhockey3]

I would think 4gb 128bit especially if you would be ultilizing over 2GB of memory. Because memory bandwith doesn't matter all that much unless your dealing with over 1080p

 

[MarkW]

Neither is better.

4GB is better than 2GB because newer games sometimes need more memory.
256 bit is better because it allows the video card to get data it needs to display faster.

Starting next year, nearly all video cards will come with between 4GB and 16GB HBM2 memory, and will have at a minimum 512 bit busses, with many having a 1024 bit bus.. Both are huge jumps over all but the very top end of today's cards.

 

[sYankOv]

Hmm and can you tell us how much will these beasts cost and what is the difference between HBM2 and GDDR5 ?

 

[MarkW]

Once they come out, then we can tell you that info.

 

[ajhockey3]

HBM is stacked right ontop of the GPU die itself. Makes it generally hotter. Makes the card smaller because you don't need to put the memory chips on the card PCB (thats how the Fury nano exists). the bandwith is insane. 512GB/S on the Fury series of GPU's. AMD claims HBM is more power saving then GDDR5 and I belive that.
http://www.amd.com/en-us/innovations/software-technologies/hbm

 

[sYankOv]

HBM is stacked right ontop of the GPU die itself. Makes it generally hotter. Makes the card smaller because you don't need to put the memory chips on the card PCB (thats how the Fury nano exists). the bandwith is insane. 512GB/S on the Fury series of GPU's. AMD claims HBM is more power saving then GDDR5 and I belive that.
http://www.amd.com/en-us/innovations/software-technologies/hbm

But isn't 512GB/s too much ? I am not an expert but I think there aren't games demanding do much bandwith? Correct me if im wrong..

And one more question - What are the most important specifications for a gpu ?

 

[MarkW]

This is a picture of the Fiji GPU is now shipping in the AMD R9 Fury X, Fury, and Nano video cards.

Those 4 bumps surrounding the big GPU in the middle are 4 stacks of HBM (High Bandwidth Memory). 1GB of memory each, and 256 bits of bandwidth each. Everything there is sitting on a massive silicon interposer, which routes all of the bandwidth "wires" to and from the GPU in the middle. So those video cards end up with 4GB of memory and a 1024 bit wide data bus.

HBM is very slow, but very wide memory. And since it is physically located so close to the GPU, it can function on very low power.

HBM2, which will be used on next years video cards will be able to have up to 8GB per stack and as little as 1GB still. So video cards next year will have as little as 4GB of memory, and as much as 32GB of memory.

GDDR5 was very fast, hot, and power hungry. But the problem was that it was creating major power (and heat) problems for all video cards, not to mention eating so much space, that they were not going to be able to keep expanding the memory on video cards. Something had to give. HBM is the replacement for GDDR5. It runs very cool, and saves tons of space, which means the video cards will be much smaller than the older ones.

Important specs of a GPU? Memory, bandwidth, and processing units. It takes all 3 of those to be able to process today's games fast enough to be able to enjoy them.