DDR 400 faster than RDRAM 533

[hk10Mbps]

DDR400 PC3200 200 MHz 64 Bit 3.2 GB/s
RDRAM 533 PC1066 533 MHz 16 Bit 2.1 GB/s

Is it true?

 

[DynaOne]

No -RDRAM 533 1066 is 4.2 Gb/s - but Granite Bay with DCDDR with match this with cheap 2100 DDR memory.

 

[hk10Mbps]

Please tell me the bandwith of:
RDRAM 533
DDR 400
Dual Channel DDR 400

 

[Adul]

Originally posted by: DynaOne
No -RDRAM 533 1066 is 4.2 Gb/s - but Granite Bay with DCDDR with match this with cheap 2100 DDR memory.

youn are thinking dual channel pc1066 or are you thinking the 32 bit pc1066?
16 bit rdram pc1066 is 2.1
dual channel rdram pc1066 16 bit is 4.2
32 bit rdram pc1066 is 4.2

 

[hk10Mbps]

> 16 bit rdram pc1066 is 2.1
If it is true, is it slower than DDR 400?

 

[DynaOne]

Agree with Adul - but if you are looking for performance you would only go with a 4.2 G/s RDRAM solution (if you are limiting yourself to RDRAM).

DDR 400 is the slowest of those listed, as DC DDR 266 (2X2X266= 1066) also yields 4.2 G/s. See Anandtechs most current article to compare DDR 333 vs 400.

Of course you can run DC DDR with 333 (and maybe 400) DDR memory and be even higher than 4.2 G/s - but tidbits out there suggest (as with DDR 400 not being any faster than DDR 333) that until the 533 bus speed is increased (667 with Prescott Q2 03) that improvements over using 266 memory will be limited.

 

[AndyHui]

No, it's not.

No one makes a single channel implementation of 16-bit RDRAM, that's why the bandwidth of PC1066 is taken to be 4.2GB/s.

 

[hk10Mbps]

So what is the bandwith of DDR 400 and RDRAM 533?

 

[AndyHui]

OK.

DDR400 DDR SDRAM, 200MHz double clocked, single channel implementation: 3.2GB/s.

PC1066 RDRAM, 533MHz, 16-bit single channel implementation: 2.1GB/s.

No one makes a single channel 16-bit RDRAM chipset. 16-bit RDRAM needs to be run in pairs. 2 x 2.1GB/s = 4.2GB/s.

Therefore RDRAM is faster.

In regards to your Granite Bay vs RDRAM problem;

GB uses 2 PC2100 (DDR266) SDRAM channels, for a total bandwidth of 4.2GB/s.

This is the same bandwidth as the RDRAM I pointed out above.

 

[Lonyo]

Bandwidth isn't all speed, doesn't DDR have less latency than RDRAM, meaning if they have the same bandwidth, wouldn't the DDR be the better idea due to latency and cost both being lower?

 

[AndyHui]

Cost might be lower, but in terms of latency, PC1066 RDRAM is very close to DDR SDRAM. The RDRAM chipsets are designed to hide latency anyway, so latency isn't really a consideration.

RDRAM's latency is inversely proportional to its clock speed, so the faster RDRAM is, the less latency it has.

 

[cmdrdredd]

what is the equation to figure out the theoritical bandwidth of memory solutions?

 

[AndyHui]

Check out the

What is DDR SDRAM and
What is RDRAM FAQs.

 

[hk10Mbps]

My another hope is SIS658, it support AGP8X and Dual channel RDRAM. But it doesn't seems to support Hyper-Threading. Go here:
http://www.sis.com/products/chipsets/oa/pentium4/r658.htm
http://www.sis.com/news/press/sisr658.htm

 

[AndyHui]

Alright, I've given you the calculations for bandwidth. Why do you want RDRAM? Normally I am an advocate of the RDRAM chipsets, but with Granite Bay, there is NO reason to go with RDRAM.

Intel is not going to allow SiS to support HyperThreading.

 

[boyRacer]

GB and the RDRAM are neck and neck... http://www.ocworkbench.com/2002/asus/p4g8x/p4g8xp3.htm

 

[Sharkmeat]

16 bit vers 32 bit 1066 RDRAM = Same diff,s in speed.Both are dual channel but 16 bit has a longer pipe line.If you have a program that would take 2 years to work out then you may see the diff,s in time.I ran a band width and it don't show squat diff,s in 16 and 32 both say est 4.2 gb/s true is 34043 reading 16 bit on a P4t 533-c board.

 

[AndyHui]

16-bit has a longer pipeline? Huh?

The 32-bit RDRAM implementation on the ASUS P4T533 is simply 2 16-bit channels multiplexed together. It has nothing to do with pipeline.

 

[Sharkmeat]

P4t533-C has 4 slots = 2banks for the 16 bit RDARM = longer tracers = a pipeline to flow the current to the cpu the Pt4 533 only has to slots for 32 bit Rdram.32 or 4200 speed.But both run no diff in speed.or if so you want know the diff,in real time use.

 

[AndyHui]

Traces are not pipelines. Traces on motherboards are all carefully laid out and calculated and will not make a difference. If anything, the traces on the P4T533 are longer since they have to route to the back of the RIMM slot.

Most benchmarks, at the time the P4T533 was released, showed that this board was actually SLOWER than the regular P4T533-C.

 

[Budman]

Intel Granite bay using PC2700 running at 166mhz kills all. end of discusion......

it's done,Rambus is dead.

 

[Mrburns2007]

Originally posted by: Budman
Intel Granite bay using PC2700 running at 166mhz kills all. end of discusion......

it's done,Rambus is dead.

 

[ScrapSilicon]

Originally posted by: AndyHui
Alright, I've given you the calculations for bandwidth. Why do you want RDRAM? Normally I am an advocate of the RDRAM chipsets, but with Granite Bay, there is NO reason to go with RDRAM.

Intel is not going to allow SiS to support HyperThreading.

figures

Via as well on HT..?:

 

[AndyHui]

Word is that Intel will not allow any 3rd party manufacturer to support HT on their chipsets. Maybe with the exceptioon of ServerWorks, but that's different.

 

[rip22]