Corsair 2.0 vs. Samsung 2.5

[Guest]

<A HREF="http://store.yahoo.com/buyaib/samormajbran.html" target="_new">samsung high memory</A>

i like toasted cpus but not AMD-inside.

 

[Vince604]

haha.. I guess you can't go wrong with Corsair.

just the price is a little above average.

 

[lhgpoobaa]

worth it for the sexy black heat spreader if nothing else LOL

<font color=blue>All religions are true, for a given value of 'true' - Terry Pratchett.</font color=blue>

 

[vfxxx]

Can someone tell me what is difference in Cas2.0 and Cas2.5? Howcome no one mention Kingston memory?

 

[lhgpoobaa]

READ the FAQ at the top of this forum... it will explain it better than i can.

<font color=blue>All religions are true, for a given value of 'true' - Terry Pratchett.</font color=blue>

 

[8235k8hta]

"Howcome no one mention Kingston memory?"
too expensive.

 

[8235k8hta]

you wait for 2ms with the CAS2 and 2.5ms with CAS2.5. roflmao.

The <A HREF="http://forumz.tomshardware.com/hardware/modules.php?name=Forums&file=viewtopic&p=49770#49770" target="_new">explan</A>

 

[AMD_Man]

Actually, that's completely WRONG. CAS is a latency but it has no fixed length of time. CAS2 means to wait for 2 cycles and 2.5 means to wait for 2.5 clock cycles. Depends on what the RAM runs at, the length of a clock cycle differs. For example, PC133 and PC2100 have 7.5ns (that's <b>nanoseconds</b>) clock cylces. So if you have CAS2, you wait for 15ns. CAS2.5 would be 18.75ns.

PC2700 has 6ns clock cycles. So that's 12ns for CAS2, 15ns for CAS2.5.

As you can see, CAS2.5 PC2700 has the exact same latency as CAS2 PC2700. Since AMD motherboards run at 266MHz, they never take advantage of the extra bandwidth and since many people run their PC2700, they won't see an improvement in latency either. Therefore, unless you run your PC2700 at CAS2, you'll be better off saving some money with PC2100!

<b><i>"A penny saved is a penny earned!"</i></b>

 

[8235k8hta]

i think you didn't follow the "Explan" link. roflmao (second)

 

[8235k8hta]

moreover theire is a error in your explan.

CAS2 => you wait 2 clock cycles not 15ns
CAS2.5 => 2.5 clock cycles not 18.75ns

you have 7.5ns memory but 1 cycle clock time is under 7.5ns.

Geez.

 

[AMD_Man]

What are you talking about? PC133 and PC2100 both run at 133MHz. PC2100 outputs processing data twice per cycle. Anyway, so 1000/133 = the memory rating in ns which you see on the RAM. For PC133 and PC2100, that's approximately 7.5ns. Therefore, the length of 1 clock cycle is 7.5 ns.

2 cycles = 15ns in this case.

<b><i>"A penny saved is a penny earned!"</i></b>

 

[8235k8hta]

ok.

here is the link from THG which explains memory clock cycle bases in 1998.
minimum clock cycle of 5ns for an old EDO memory with a global 80ns access time.

<A HREF="http://www.tomshardware.com/mainboard/98q4/981024/ram-04.html" target="_new">http://www.tomshardware.com/mainboard/98q4/981024/ram-04.html</A>

now the question is yours: what are you talking about?


i think you can calculate an average cycle time with something like that:

- you know the memory global access time.(1)
- you know the number of cycles needed by the current memory. (2)

avg clock cycle time = (1)/(2)

fo some corsair pc3200 @CAS 2-3-3-5-1 (400Mhz DDR,200Mhz realtime), you have:

avg clock cycle time = (1/200) / 14 = 0.36ns
<P ID="edit"><FONT SIZE=-1><EM>Edited by 8235k8hta on 06/23/02 01:46 AM.</EM></FONT></P>