effective memory clock speeds

[valve]

Why are the effective memory clock speeds of some cards 8 times the actual clock speeds? GDDR5 is only quad-pumped, so the effective clock speeds should only be 4 times the actual ones, right?

 

[-rascal-]

5 minutes ago, valve said:

Why are the effective memory clock speeds of some cards 8 times the actual clock speeds? GDDR5 is only quad-pumped, so the effective clock speeds should only be 4 times the actual ones, right?

 

 

Can you give an example there the effective speed is 8x?

EDIT: 

GDDR5X and GDDR6 is 8x the actual frequency -- Octa Data Rate

GDDR5 is 4x -- Quad Data Rate

[Levent]

I believe OP is talking about HBM stuff, afair (and please correct me if I am wrong) HBM memory can be stacked, thats why its effective memory speed multiplier is much higher.

[valve]

10 minutes ago, Levent said:

I believe OP is talking about HBM stuff, afair (and please correct me if I am wrong) HBM memory can be stacked, thats why its effective memory speed multiplier is much higher.

I don't actually know what HBM is ... Do you mind though explaining to me what HBM is and maybe how that's related to GDDR?

[hollyh88]

8 hours ago, valve said:

I don't actually know what HBM is ... Do you mind though explaining to me what HBM is and maybe how that's related to GDDR?

gddr is what nvidia uses in its consumer gpu's hbm is what amd used in some of it's consumer gpu's. both are vram for the gpu. hbm however is more than gddr but also expansive. 

[hollyh88]

 

gddr ^

 

info about hbm:  https://en.wikipedia.org/wiki/High_Bandwidth_Memory