Could 2 GPU dies use the same HBM memory stack if they are sandwiched together?

[joshua123033]

If you had 2 of the same graphics cards, and they both had HBM memory, could they have their GPUs sandwiched together and use that collection of RAM? (it would be hard since 1 graphics card would have to have its GPU on the opposite side of its PCB).

I was wondering this so don't judge me if this idea isn't that good.

 

[COLGeek]

Maybe (but not as a user project). The issues could be heat and electrical interference between the two "halves" of the combined device.

Similar GPUs have been sold, but they were typically longer than normal GPUs as opposed to thicker. This helped to spread components apart to deal with these issues.

For example: https://www.amd.com/en/products/professional-graphics/radeon-pro-duo-polaris

https://techreport.com/review/26279/amd-radeon-r9-295-x2-graphics-card-reviewed

 

[TJ Hooker]

There have been a number of dual GPU graphics cards released in the past, that basically sandwich two cards into one. But each GPU would only have access to half of the total VRAM on the card. I'm not aware of any (gaming) card that has two GPUs sharing VRAM.

You'd need some sort of high speed switch for all the VRAM data pins, to route data to either GPU as necessary. That or have special DRAM chips that have two sets of outputs. These sort of things may not exist, or be impractical. You'd also basically halve the memory bandwidth available to each GPU compared to each having their own VRAM, assuming the memory bus width and transfer rate remain the same.

Edit: I interpreted your post as asking if both GPUs could share the same pool of VRAM.

 

[USAFRet]

If you had 2 of the same graphics cards, and they both had HBM memory, could they have their GPUs sandwiched together and use that collection of RAM? (it would be hard since 1 graphics card would have to have its GPU on the opposite side of its PCB).

I was wondering this so don't judge me if this idea isn't that good.

Can a GPU be built with 2x main chips? Sure.

Can you do this at home? No.

 

[joshua123033]

I don't blame you guys for not understanding my question. I was really vague with it. I didn't want to put 2 GPUs into 1 graphics card. I wanted to have 2 graphics cards with 2 GPUs using HBM. I wanted the 2 graphics cards put into its own PCI-E slots and I wanted the 2 to be connected by the GPU only. It would be weird as 1 graphics card would have to be facing backwards. Since they would be both connected by each HBM stack (as both GPU dies would be touching), I was wondering if they could then share their memory that way.

 

[USAFRet]

I don't blame you guys for not understanding my question. I was really vague with it. I didn't want to put 2 GPUs into 1 graphics card. I wanted to have 2 graphics cards with 2 GPUs using HBM. I wanted the 2 graphics cards put into its own PCI-E slots and I wanted the 2 to be connected by the GPU only. It would be weird as 1 graphics card would have to be facing backwards. Since they would be both connected by each HBM stack (as both GPU dies would be touching), I was wondering if they could then share their memory that way.

This HBM?
https://www.amd.com/en/technologies/hbm

No.
And again, this not something you build or enable at home, but rather simply a different memory config.

 

[TJ Hooker]

Still not sure I understand. What do you mean "they would be both connected by each HBM stack"? But I don't see how it'd make any difference whether the VRAM is HBM or regular GDDR. Regardless of the physical configuration, in order for two GPUs to share the same VRAM you'd run into the issues I mentioned in my first post.

As far as your proposed physical configuration, having both GPUs touching with nowhere for a heatsink to make contact with the GPU would likely be a nightmare for cooling.

 

[joshua123033]

Thank you all for answering my question. It was actually a question that was on my mind for some time.