Athlon & RDRAM?

[Sp3nce]

I was just thinking today, we've got P4 and RDRAM, SDRAM, and now DDR. Why hasn't RDRAM been adopted for the athlon?

 

[BeauJangles]

Because AMD has chosen the DDR route.

 

[Sp3nce]

That seems to me like the best combo, the fastest processor, and the fastest memory.

 

[MadRat]

More like AMD doesn't want to invest capital in a RDRAM chipset when it has absolutely no benefit to the Athlon-family of processors.

 

[Sp3nce]

Why couldn't VIA just take it upon themselves. You mean to tell me that a RDRAM powered athlon system wouldnt be faster than a DDR based solution?

 

[Pabster]

Sp3nce wrote:

"Why couldn't VIA just take it upon themselves."

Oh, christ. VIA + RAMBUSt? You're talking about certain disaster. No thanks.

Right now, no, RDRAM would provide zero benefit to the Athlon platform. The only thing it would do is increase the mainboard costs, cause you to spend twice as much on RAM modules.

 

[Sp3nce]

My question is why? Why would a system not benefit from faster RAM; in this case RDRAM?

 

[QuestionsandAnsweres]

its sordof like the pentium 3 didnt benifit from RDRAM

Pentium 4 was MADE TO USE RDRAM. dont want to go into detail cause im to druged up (dont ask)

 

[Sp3nce]

I was reading the X BOX review on anandtech and he said that the PS2 has a "128-bit MIPS processor ", using RDRAM. Why does a MIPS processor benefit, and an athlon XP not?

 

[ST4RCUTTER]

Sp3nce,

The Athlon processor doesn't benefit from RDRAM because it doesn't have the bandwidth that the P4 has. The P4 currently has a 3.2GB/s path to memory. The Tehama-E chipset should push that even higher. The Athlon on the other hand currently has 2.1GB/s of bandwith. So tying a 2.1GB/s processor to memory that's capable of 3.2GB/s will result in wasted memory bandwidth...even with the pre-fetch on the Palomino. This will probably change with the Hammer, and maybe even the Thoroughbred. We'll have to wait and see. AMD does have a license to use RDRAM. Remember too that memory bandwith is not the same as memory performance or efficiency. The chipset of the P4 has to use aggresive pre-fetch to reduce the latency of RDRAM. Dual channel DDR while more expensive for the motherboard manufacturer, is much faster due to its low latency.

 

[Sp3nce]

Thanks ST4RCUTTER for the great response. That is exactly what I wanted to know.

 

[Alex]

the athlon just wasnt built to take advantage of the extra bandwidth

 

[ST4RCUTTER]

No problem. Interestingly enough, I read some news over at the Inquirer that the Intel DDR board benched faster (in some benchmarks) than its RDRAM counterpart, due mainly to its lower latency...the SiS and Via boards are supposed to be even faster.:Q

 

[sandorski]

Yea, RDRAM seems not to be even much better with the P4. It's boiling down to RDRAM's only advantage being it's much less neededmamount of traces, it's not "faster" per se. Eventually someone is going to come out with a dual DDR setup and RDRAM will be clearly outclassed. IMO.