Rambus Takes Another Shot At High-End Memory

An anonymous reader writes "Tom's Hardware is running an article about Extreme Data Rate memory (XDR DRAM for short), which was developed by Rambus and now entered mass production in Samsung's fabs. Right now, Rambus says the memory is only for high-bandwidth multimedia applications such as Sony's Cell processor, but the company ultimately hopes to push XDR into PCs and graphics cards by 2006. Time will tell if Rambus has learned from the mistakes it made with RDRAM a few years ago."

Comments

latency?

[tomstdenis]

8GB/sec is good but not if the latency is higher than DDR.

People seem to forget that the "Random" part of RAM is kinda crucial.

Tom

Rambus seems to forget

[onyxruby]

Rambus seems to forget their attempt to shanghai the entire memory business through fraud a few years ago. Perhaps they should be reminded that the IT community has not. They should sell their IP and disolve themselves to avoid losing their stockholders any more money.

I have adamantly refused to purchase any system that would use their memory for years, and more to the point have made that decision for others that depend on me making that decision. That's a lot of computers over the years were talking about. I am also far from alone.

Re:The numbers don't lie!

[forkazoo]

That would be an unusual special case. First off, most (non realtime) 3D rendering isn't terribly bandwidth or latency sensitive. Assuming the CPU is fast enough that it isn't the main bottleneck, such apps will tend to be more sensitive to latency than to bandwidth. When tracing a ray, for example, one may need to access data from all over memory to do hit-testing, but not need very much information in total. So, the relatively poor latency characteristics of RDRAM don't really suggest a keen funtansticness for 3D rendering. And, considering that current single channel DDR400 has as much bandwidth as dual channel RDRAM did... Well, I'm just surprised that your app would have such a benefit. I'd suspect that there were other differences that caused such a difference in your benchmarks. Do you have any more specifc information, such as what app you use, what sort of scene it was, and what the test systems were?

If you were dealing with slightly different steppings of the same CPU (I assume a P4?) it would be possible that you had two CPU's of the same clock speed, but the newer stepping was less efficient per clock. The P4's, over time, have been tweaked to be less and less efficient over time, in order to facilitate higher clock speeds. RDRAM was popular with the very first generation of P4's, so it'd be logical that the benchmark you saw may have been a newer core. That shouldn't explain a 20% speed difference, but it's an example of a small thing that may have contributed to making the memory system appear to be the determinant item in performance.