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True bandwidth differences.

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dippy_skoodlez

Member
Joined
Mar 19, 2003
Location
In front of my computer
ALright... Been talking about people doing some extreme OCing with 250fsb and stuff, and someone complain that cas3 is worthless. Well, I did some tests. Heres what I found wisth Sisandra.

@ 133mhz:

Cas 2 = ~1922Mb/s
Cas2.5= ~1920Mb/s
Cas 3 = ~1911Mb/s

@ 166mhz

Cas 2 = ~2432Mb/s
Cas2.5= ~2429Mb/s
Cas 3 = ~2426Mb/s

@200mhz

Cas 2 = ~2912Mb/s
Cas2.5= ~2909Mb/s
Cas 3 = ~2900Mb/s

This is single channel, On a DFI Infinity and 256Mb Pc4000 Adata.

Whats the big deal with Cas 2 Vs cas3? :confused:
 
OP
dippy_skoodlez

dippy_skoodlez

Member
Joined
Mar 19, 2003
Location
In front of my computer
Bios24 said:
WOW. Anyone want to back this up? Does timing really make no difference at all???


I have screenies if you want em... one at each FSB and each CAS. All run CAS-3-3-11 single channel on my infinity.

But, it has a crooked socket, and is throwing my SLK way off. RMA time. :bang head

I may be able to stick my WD in this PC and pull the screenies off if you want me to.

I dont see how BH-5 is worth 3x the price of my Adata.... :confused:
 

julianba

Member
Joined
Jul 26, 2003
Location
NJ,USA
Cas isn't as important as trcd and tras in memory bandwidth.



Dippy_skoodles, any chance you could test cas-3-3-11 versus cas-4-4-11? That might show more of a difference in bandwidth.
 

TheGame240

Member
Joined
Oct 23, 2002
Location
Muscle Shoals, AL
From what I've always understood, the real difference in CAS timings is in access time, not bandwidth. In other words, your findings are exactly as they should be. However if you used a different test (something that accessed memory frequently not just big chunks) you would start to see a bigger gap in CAS 2 and CAS 3 settings. Also this is why memory timings don't play as big of a role in PIV systems. Less work per clock cycle, therefore less memory access per clock cycle, less importance in fast (access wise) ram and more imporatance placed on large bandwidth.
 

obsolete

Member
Joined
Dec 30, 2003
Location
MN
Yes, Cas 2 vs Cas 3 reflects access times. Load windows at Cas 2 & browse around & load windows at Cas 3 & browse around. If you can't notice the difference...... :beer:
 

Gautam

Senior Benchmark Addict
Joined
Feb 4, 2003
Location
SF Bay Area
Funny how everyone puts so much faith in such a useless benchmark.

The Sandra memory bandwidth benchmark is a memory bandwidth benchmark. All it does is test raw bandwidth. Of course timings won't make a difference there. Try out PIFast, SuperPI, 3DMark01, and you'll see a completely different story.

Although CAS isn't nearly as big a deal as tRCD.
 

meionm

Member
Joined
Mar 8, 2004
sisandra measures bandwith and it usualles with timings, use super pi or prime 95 benchmark, my super pi test and result
super pi for 1M
280-2.5-4-4-7------36sec
280-2.5-3-4-7------35sec
280-2.5-3-4-6------34sec