Who's the stupid one? DDR vs. SDR

[Kanaz]

I was at a vendor of mine, and I ran into one of my competators (I own a small computer shop). He was buying a GF4 TI4600 for his XP2000+ using PC-133 RAM.

I asked him why, if he was buying such a nice machine, was he using PC-133 instead of DDR. He told me that I was dumb, because PC-133 is faster. This, he said, is due to the CAS latency. So...is he right?

P.S. If he is or not, what is better? 256MB DDR-266, or 1GB SDR-133?

-"LD provides the USB disk makes you portable your data everywhere as easy as possible"

 

[eden]

The memory size has little effect on performance, depending on the OS. Someone who has 256 and one who has 1GB in Win98, the 1GB guy is a radical moron, unless he is using graphical editing suites, and even then, Win98 has very little efficiency in managing over 512MB.
In WinXP, the jump from 256 to 512MB is often extremely beneficial, but that guy even if he used WinXP, is an idiot nevertheless, again unless he uses intensive rendering.

He's more idiotic with his claim. CAS latency DOES LITTLE compared to what bandwidth increases do!
At maximum, CAS 2 can increase 10% which is rare, going from SDR to DDR, can vary from 10% to over 20%. This guy, needs to be fired or go bankrupt for his lack of knowledge and hypocrisy!

In conclusion to your final question, there is no answer, it all depends on the OS, the usage purpose AND the processor platform!

--
I guess I just see the world from a fisheye. -Eden<P ID="edit"><FONT SIZE=-1><EM>Edited by Eden on 10/27/02 09:10 AM.</EM></FONT></P>

 

[knowan]

In general DDR is 10-20% faster than SDRAM. The latency does have an effect (especially on AMD systems) but DDR is now available at identical latencies as SDRAM.

In general for every .5 differency in CAS latency, there is a 5% or less difference in performance.

So DDR running at the same latency is up to 20% faster. But wait, there's more.

You also have to take into consideration the chipset difference. He has to be using either a SIS or a KT133 or KT133a chipset. The kt266a and the kt333 DDR chipsets give about another 5% boost over those older chipsets (except the KT133a, which is almost as fast).

So yes, your friend is an idiot. DDR is up to 25% faster. In pratice it's more like 15-20%, but that is a noticible difference.

And there is still more difference. SDRAM is topped out at pc-133 speeds. DDR is available at pc2100 (which the above equation is based on) pc2700, pc3100, and even faster. With identical CAS latencies, PC2700 is roughly 5% faster than PC2100, and PC3100 is roughly another 3% faster. This continues up the line with the faster speeds, but generally those aren't available in lower CAS latencies. SDRAM of course isn't available faster than pc-133 speeds.

So now you're talking roughly 30% faster for DDR.

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[juin]

yes SDRAM as faster timming that DDR but DDR got much more badwith 2X or more so DDR is much faster about 25% on XP 50% on P4

Now what to do??

 

[eden]

I wouldn't go as far as 50% on P4s, more like 30%. However it is indeed clearly noticeable.

--
I guess I just see the world from a fisheye. -Eden

 

[juin]

30% make some calculation it even more that 50%.

Now what to do??

 

[eden]

Show me benches.

--
I guess I just see the world from a fisheye. -Eden