256bit vs 512bit GPU

in case a mod reads this, we should add a “hardware” topic aswell :slight_smile:

so, as far as i know, the difference between a 256bit and a 512bit GPU memory interface is the amount of data it can read/write to VRAM at the same time, witch does not really seem like a big deal in gaming, but for rendering? in rendering you store big chunks of data at once, so will a 512bit interface have a huge impact on rendering time?


If you’re asking about rendering a scene using Cycles, it only takes a couple of seconds maybe to load the scene in VRAM whereas it may take many minutes to render. Better to emphasize number of CUDA cores on a Nvidia GPU at this time (with development continuing on adding functionality to Cycles when using AMD GPU this may change relatively soon).


Edit: sorry, almost forgot to mention that amount of VRAM will also be important (ie get enough to fit your scene otherwise it will fail to render).

Unfortunately @RCAFBrat you appear to be confusing GPU PCIe bandwidth with GPU vRAM bandwidth.

The PCIe bandwidth is how fast data can be fed from the CPU/RAM to the GPU via the PCIe connection lanes.

The 256/512bit finalbarrage is asking about is how fast the GPU (CUDA for example) cores can communicate with the GPU vRAM.

There are two main factors in what affects a GPU’s memory bandwidth, the first is its clockspeed (MHz). The higher the clockspeed the more memory transfers a GPU can do per second.
The ‘bit’ width eg 256bit is how wide the data transfer between GPU cores and the vRAM is, or how much data can be sent in a single transfer.

Having a higher # of ‘bits’ in the bandwidth isn’t necessarily useful if your GPU doesn’t have the capability to process that data. That’s why greater core counts go hand in hand with faster, and wider memory connections, to keep the GPU cores fed.

Judging by the usage stats I see in GPU-Z when rendering; Example GPU: 100% Memory: 63% I would say the memory is fast enough to keep the GPU working as best it can.

Absolutely right, my bad.


Np, what you answered is 99% the question people generally ask here :stuck_out_tongue: