Ddr/rd

[eddy05]

Firstly I would say that no wars should be start... I know if I didn't warn, some war like DDR_vs_RD, intel_vs_AMD or Nvidia_vs_ATi might happen.

According to Rambus' website, I found out supposely that Rambus costs cheaper, faster, bigger bandwidth than DDRram. I couldn't find any websites of DDR RAM though. If supposely Rambus is cheaper and faster then DDR, why is the world moving towards DDR? Why do most people choose DDR instead of Rambus? Is DDR RAM actually better then RDRAM?

I'm not Bias in this thread, just trying to figure things out, ask questions and hear views from the public

 

[Didou]

Shouldn't this be in storage mania ?

Anyhow, RDRAM is done by one company RAMBUS ( Rambus.com ) which licenses the technology to Ram makers whereas DDRam is concieved by a coalition of Ram makers ( JEDEC - Jedec.org ).

Let me start of by saying that I really have no respect for the Company Rambus. I'm not talking about their technology which has some interesting points, I'm talking about the people who run that company.

Last year, the web was full of news about Rambus attacking every single Ram maker for Royalties on Patents for all kinds of Ram ( SDRam, DDRam, etc... ) claiming everyone used patents of theirs without consent.

I'm very glad they got their Hineys kicked for every case they started.:grinthumb

Now about the RDRAM. It's main advantage over DDR is Bandwidth. One of the drawbacks is latency. Rdram has much higher latencies then DDRam. The other thing that I don't like about it is the fact that you need two memory modules ( a bit like Simms ) allthough they should be coming out with a newer version of RDRAM which doesn't require two modules.

If nVIDIA would put out a Dual Channel DDRam chipset for P4, there really wouldn't be any need for Rambus anymore. Dual Channel RDRam can achieve 3.0 - 3.2 ( 1.5 GBS *2 ) GBS whereas the dual channel DDRam on the nForce is capable of 4.2 ( 2.1 GBS * 2 ). The problem is that the Athlon cannot use such amount of bandwidth due to the FSB ( 133 DDR - 266 mhz - 2.1 GBS ) but it would fit perfectly for the P4 & it doesn't even have the high latencies RDRam does.

 

[Rick]

I agree with the above in many respects. The company itself has proven a bit crooked, and with the recent infringement litigations, things do not look good for Rambus.

On a technical level, RDRAM offers two things:

1.) Scalability
2.) Bandwidth

Scalability:
The awesome thing about RDRAM and the only reason I respect the designs of RDRAM is this feature. Since it's datapath is only 16-bits wide, you can really scale RDRAM for servers etc.. While expensive, high-end, multiprocessor servers and workstations could have 4 memory paths for every 1 that current DRAM has. Since Rambus can be "quad pumped", you effectively get twice the bandwidth on the same PCB... Once again, only useful in an extreme computer enviroment. This is not for your average user.

Bandwidth:
Current RDRAM can support 3.2Gb/sec, which is twice as much as DDR in its original incarnation. Of course, now DDR is raising its clock speeds and can match RDRAM's bandwidth. But this was not the case last year.



Those were the plusses I think. The minuses have always been touted as expense and real-world performance was not very good. So even though you are getting more bandwdith, new architecture and higher scalability, you are still getting decreased performance in the real world - And that's what counts.

This article a found awhile back might make some people think differently about RDRAM:
http://www.dewassoc.com/performance/memory/rdram_v_sdram.htm

I personally don't like RDRAM, despite what the article says. It just doesn't perform as well. Give me numbers and fair prices with a less shady company, and then I'll consider Rambus.

 

[Vehementi]

Just some more info on the topic:

R.I.P. Rambus

 

[uncleel]

Rambus is dead :dead:

 

[eddy05]

After a bit of reading, I see that RDRAM is definitely better then SDRAM, though a bit more costly. I do not know about the latency of DDR Ram, but does it really matter? I see that these latancies are measured in nanoseconds, which is perhaps too fast for us to be aware of? And there are articles which showed the effectiveness of RDRAM over DDR. I'll post the link once I found it.

 

[uncleel]

Sony Beta-Max was better than VHS, but where is it now? :dead:

 

[Arris]

In the attic/garage/loft gathering dust
I partially blame the first P4's and the early P4 chipsets from Intel for not fully taking advantage of thee Rdram. By the time the better chipsets/improved socket came out for the P4, DDR ram had seized the advantage by being cheaper and providing good performance for its price.

 

[eddy05]

I remembered...

that Intel released the first Pentium 4's (yah, mine was one of the first too...) it came with PC133 SDRAM which shocked the whole world off their shoes... Then, it made RDRAM, which is supposed to be high performancing, lost the market and partially cause its downfall. So you guys hate intel's marketing tactics? My friend sure do, that's why he bought an Athlon XP instead.. (Partially because it's cheaper)

 

[Didou]

Intel released the P4 with an RDRAM platform first ( i850 ) then moved on to SDRam ( i845 ) then DDR ( i845-D ).

Intel had allready released an RDRam platform before the P4. It was the I820 for P2/3. It was a failure because it was very expensive & the performance premium over SDRam was non existant ( i815 with SDRam actually performed better ). So they reelased a hybrid chipset, the i820 with MTH ( memory translator hub ). We all know what that did.

 

[SNGX1275]

I have another question - similar topic so I thought it should stay in this thread. Ram went from 133 to 266 then to 333. Why 333? Shouldn't it have gone to 400?

 

[Didou]

It actually went this way ( as far SD/DDRam ) :

• PC100 - 100 MHZ
• PC133 - 133 MHZ
• PC1600 - 100 MHZ DDR ( 200 )
• PC2100 - 133 MHZ DDR ( 266 )
• PC2700 - 166 MHZ DDR ( 333 )

Maybe the speed bumps for Ram aren't easy to produce ( heat issues, etc... ). For example, the only PC2700 modules available are CAS2.5. Maybe they can't get them to be sufficiently stable at CAS2.

It might also be that Ram companies try to cash in on every single speed possible.

PS. Please correct me on the speeds above if I'm wrong.

 

[eddy05]

There's also PC150 and DDR300. There's even a PC3000 (DDR370) selling in the market... CORSAIR XMS3000 256MB 370MHz DDR SDRAM

 

[Arris]

SiS jumping on the DDR400 bandwagon
Jedec and the DDR-II specifications