is there a big difference between cas 4 and cas 5?

magick · 27 Jun 2007 at 16:03

Is there much of a real world difference between speeds CAS 4-4-4-12 and CAS 5-5-5-15? And does the performace difference justify the difference in price?

helmutcheese · 27 Jun 2007 at 16:25

I would say yes but not as much as from 2 to 3 in DDR1.

Admiral Huddy · 27 Jun 2007 at 16:39

I think it depends on the CPU you are using. The AMD platform will benefit more from lower latencies than Intel. That said, I've never noticed any major performance boost when it comes to lowering the timings in either symphethic or real time benchmarking. Not worth the extra cash IMO.

stickroad · 27 Jun 2007 at 16:47

magick said:
Is there much of a real world difference between speeds CAS 4-4-4-12 and CAS 5-5-5-15? And does the performace difference justify the difference in price?

If you had two computers setup, exactly same specs but on one computer the Memory was running at 800MHZ with timings of 4-4-4-12 and then on the other computer the memory running at 800MHZ 5-5-5-15. You had to pick the system that had the tighter timings on, it would be a guess more than actually knowing that this system had the tighter timings.

So in other words no you wouldn't really notice the difference to be honest.

magick · 27 Jun 2007 at 16:50

Ok thanks i'll go Corsair 5-5-5-15 800mhz then as it's £20 cheaper. Incidently CPU will be a c2d E6320.

gurusan · 27 Jun 2007 at 18:15

I would imagine the difference would be more noticeable on an AMD setup.

agnes · 27 Jun 2007 at 20:04

for 20 quid, i would go with lower timeings

ags

helmutcheese · 27 Jun 2007 at 21:40

I was going to say that before, if £20 is only issue FFS get the better ram.

HangTime · 27 Jun 2007 at 22:03

£20 can be a significant percentage when looking at value RAM.

I've been benching superpi a bit today and haven't found a great deal of difference between 3-3-3-9 and 4-4-4-12 on my C2D rig, so I'd imagine it's a similar story for cas4->5. Seems like FSB is probably more important although I need to do some more research.

cells · 28 Jun 2007 at 02:14

HangTime said:
£20 can be a significant percentage when looking at value RAM.

I've been benching superpi a bit today and haven't found a great deal of difference between 3-3-3-9 and 4-4-4-12 on my C2D rig, so I'd imagine it's a similar story for cas4->5. Seems like FSB is probably more important although I need to do some more research.

you need a better benchmark

something that accesses the memory often and runs for a long time

helmutcheese · 28 Jun 2007 at 02:45

And the slacker the timings the worst, It will be bigger gap from 5 to 4 then from 3 to 4.

magick · 28 Jun 2007 at 03:09

helmutcheese said:
And the slacker the timings the worst, It will be bigger gap from 5 to 4 then from 3 to 4.

So where does that leave DDR3 with timings of 7-7-7-21 and 9-9-9-27 and nearly 3 times the cost?

helmutcheese · 28 Jun 2007 at 03:21

Excuse me, we are compairing apples to apples not apples to oranges, we are talking DDR2, not DDR2 v DDR3.

magick · 29 Jun 2007 at 10:58

well what's the difference between them? all I can see is the same speed as higher end ddr2 but with a higher latency.

james.miller · 29 Jun 2007 at 11:07

ddr3 is an evolution of the sd-ram standard. ddrI introduced 2 instructions per cycle (hence Double.Data.Rate). ddrII increased the prefetch buffer to 4bit (up from 2bit with ddrI). ddr3 increased that again to 8bit. that's the main advantages over ddrII, anyway. increasing the prefetch buffer and over little improvements does have an effect on latency though.

the main promises of ddr3 are around a 16% lower power consumption and much faster achievable speeds. as with ddrII (and ddrI), ddr3 has been introduced at a point where its slacker timings and its operating speed (although fastest) dont offer any real advantages over the current crop of ddrII modules.

watch this space though. because ddr3 will get very quick.

helmutcheese said:
Excuse me, we are compairing apples to apples not apples to oranges, we are talking DDR2, not DDR2 v DDR3.

perhaps he'd like to know the difference and concidering its his thread, perhaps you should help him or stay out?

helmutcheese · 29 Jun 2007 at 12:23

Also final speed in MHZ, DDR2 is not rated for 1333mhz, even though no doubt some clocks to that speed.

HangTime · 30 Jun 2007 at 07:45

cells said:
you need a better benchmark

something that accesses the memory often and runs for a long time

Well, I guess it depends what your goal is. If pure memory performance is all one cares about then maybe you wanna use a memory-specific benchmark, but for general unthreaded system performance I don't think there's much wrong with superpi 32M.

On my travels I came across this: http://www.xbitlabs.com/articles/memory/display/ddr2-oc1ghz_8.html
...which pretty much backs up what I was saying about the importance of FSB relative to timings. As you can see, DDR2-667 at 4-4-4-12 gets beaten comprehensively by DDR2-800 at 5-5-5-15. Heck even at 3-3-2-8 it can't live with it.

helmutcheese · 30 Jun 2007 at 13:32

James.miller why are you a total ***** and I thought you had me on ignore. :rolleyes:

I did not realise he was wanting info, I though he was pointing out a fact so you need to learn to stop getting on my case or I will report you to staff as your a total lamer, this is the 3rd thread you are doing so in.

james.miller · 30 Jun 2007 at 13:35

go ahead

you talk to people like that and wonder why they get on your case?

helmutcheese · 30 Jun 2007 at 13:38

You started it and I have just reported you. so I hope thats the end of it, you aint bulletproof as you have 1000's of posts, look at the behaviour warning thread 2 weeks ago.