Where is QDR RAM?

[Haswellx86]

I just learned about QDR RAM, so what happened? Why isn't it in the market? Or is it just a concept and we are figuring out yet?

[dilpickle]

https://en.wikipedia.org/wiki/Quad_Data_Rate_SRAM

https://www.reddit.com/r/buildapc/comments/2x8z77/discussion_do_you_think_we_will_ever_see_qdr_ram/

 

These two links answer your question. TLDR it exists for specialized applications and its very expensive and complex.

[Guest]

Quote

 the data transfer can be treated as a simple point-to-point unidirectional transfer. In such a simple transfer, it is no longer essential for signals to fully propagate within a cycle; they merely need to arrive coherently, marshaled by a special signal called "strobe".

Is the best answer I could find for the question "why we don't use or see this".

 

Wiki quad data rate.

 

 

[Zodiark1593]

Isn't GDDR5 and sucessors a form of QDR memory? From what I recall, the effective transfer rate of GDDR5 is at 4x the actual transfer rate. So a GDDR5 module with a rated speed of 1750 MT/s would have an effective speed of 7000 MT/s. This is in comparison to regular DDR, where the effective speed (example, 2666 MT/s) is 2x the actual speed (1333 MT/s).

 

So using my GTX 960 for an example, ((1750 MT/s x 4)) x 128)/8) =  112000 MB/s = 112 GB/s

And for my DDR3, ((800 MT/s x2)) x (64 x 2 channels))/8) = 25600 MB/s = 25.6 GB/s

[Guest]

4 hours ago, Zodiark1593 said:

Isn't GDDR5 and sucessors a form of QDR memory? From what I recall, the effective transfer rate of GDDR5 is at 4x the actual transfer rate. So a GDDR5 module with a rated speed of 1750 MT/s would have an effective speed of 7000 MT/s. This is in comparison to regular DDR, where the effective speed (example, 2666 MT/s) is 2x the actual speed (1333 MT/s).

 

So using my GTX 960 for an example, ((1750 MT/s x 4)) x 128)/8) =  112000 MB/s = 112 GB/s

And for my DDR3, ((800 MT/s x2)) x (64 x 2 channels))/8) = 25600 MB/s = 25.6 GB/s

The way it reads, DDR2 is the successor to QDR and DDR (1) 

 

Read somewhere P4 supports QDR.

[Zodiark1593]

42 minutes ago, ShrimpBrime said:

The way it reads, DDR2 is the successor to QDR and DDR (1) 

 

Read somewhere P4 supports QDR.

As far as I know, there was no QDR used for the system memory of a P4 PC (or any other consumer PC). P4 used SDR, RDRAM (which ran at very high base speeds, generating a lot of heat), and original DDR in later models. I think even DDR2 shortly before Conroe came. 

[Guest]

14 minutes ago, Zodiark1593 said:

As far as I know, there was no QDR used for the system memory of a P4 PC (or any other consumer PC). P4 used SDR, RDRAM (which ran at very high base speeds, generating a lot of heat), and original DDR in later models. I think even DDR2 shortly before Conroe came. 

Pretty sure the P4 is quad Front side bus. 

 

2 strobes at 266 = 533mhz. A single strobe is 133mhz. So 133 x 4 is 533mhz memory. But the data would run at 266mhz effectively. Or something like that anyways.