CAS 1.5 is doubt to work on A64 based systems......

[Tony]

The bios option was given a name, DFI decided to call it cas1.5, it could have been called cas12..infact i may mod the bios to name it cas12, its just a name and nothing more.

It is setting tight latency, just like cas2; but it is not cas1.5.

[Tony]

DDR2 667 @ 3-2-2-x is already reality and CAS latency holds nearly no performance benefit (though 3 is slower than 2 or 2.5).

Cas latency on DDR1 and DDR2 are not quite the same, but the theory of what you are saying is correct. The most important timings are TRCD and TRP, if by setting cas latency loser you are able to set TRCD and TRP tighter (there are other small tweaks also) you have basically made EB ram.

[HARDCORECLOCKER]

DDR2 and soon DDR3 makes me feel sad - so no company really will force DDR1 further.

No hope for 300MHz 2-2-2-5 on DDR1............

[guess2098]

DDR2 and soon DDR3 makes me feel sad - so no company really will force DDR1 further.

No hope for 300MHz 2-2-2-5 on DDR1............

my dream........ 350 2-2-2-5..... 2.5v

[Sephious]

my dream........ 350 2-2-2-5..... 2.5v

With DDR1, that is quite impossible.

[HARDCORECLOCKER]

my dream........ 350 2-2-2-5..... 2.5v

Hehe - I just would spend 4V on it..........

[DZVlad]

oh, THAT's why you changed your sig? I noticed you changed the 1.5 to 2. What do you mean tight latency? don't 1.5 and 2 options differ by performance means? or they just plain clones of each other? have you tried benching on 1.5 BIOS setting and the 2 one?

[HARDCORECLOCKER]

oh, THAT's why you changed your sig? I noticed you changed the 1.5 to 2. What do you mean tight latency? don't 1.5 and 2 options differ by performance means? or they just plain clones of each other? have you tried benching on 1.5 BIOS setting and the 2 one?

Right - take a look at post #35..............

[DZVlad]

aaah i haven't noticed there were three pages in this topic, sorry

but that's strange DFI has messed smthing up with that BIOS setting, though the 0.1 sec increase isn't ALL that big.

[HARDCORECLOCKER]

aaah i haven't noticed there were three pages in this topic, sorry

but that's strange DFI has messed smthing up with that BIOS setting, though the 0.1 sec increase isn't ALL that big.

Take Your time and read the whole thread and U will understand......

[RaptorRaider]

It is setting tight latency, just like cas2; but it is not cas1.5.

Could you tell us in what situation we would notice the benefit of this tighter latency?

[Eldonko]

Could you tell us in what situation we would notice the benefit of this tighter latency?

When you gain some stability using 1.5

[formyfaith]

i hate to tell you guys about this
but in my taiwanese forums, we already found out that CL1.5 is slower than CL2

and even CL1.5 works find, doesn't mean CL2 work in same speed

Thank god! finally somebody with the same thoughts.
Me and my friends here have found about this a long time ago

some how i think 1.5 is more stable than 2 under same speed^^"

True, for most of the cases, you can easily push your ram's CL1.5 speed as far as the same speed as CL2, and even if CL1.5 works find, doesn't mean CL2 will work in the same speeds. From what me and my friends have tested, CL1.5 was no good, and most of the times even slower than CL2. I've also found out that CL1.5 was more stable than CL2 under the same speeds.

[fatfreepork]

guys


they are the same speed. sometimes cas 1.5 reports faster and sometimes cas 2.0 reports faster, but i will say it again; the numbers are within variation range. cpu speed fluctuates and thats how you get different scores each time you run.

[dippyskoodlez]

The bios option was given a name, DFI decided to call it cas1.5, it could have been called cas12..infact i may mod the bios to name it cas12, its just a name and nothing more.

It is setting tight latency, just like cas2; but it is not cas1.5.

if cas 1.5 doesnt work in the bios, any "performance" differences shot down by benchmarks are now void....



if it doesn't work, then you cant compare them right now Do p4's boot 1.5?

[formyfaith]

One more thing is that after finding the maximum clock with CL2,

then change it to CL1.5 and try to pump it up more, and for most of the

cases you should see that the max mem clock goes up.

This explains why CL1.5 is more stable than CL2 under the same speeds.

(but with less performance)

[EMC2]

Just to put this to bed, so to speak...

CAS latency as normally thought of is the latency from CAS going low till when the first data is available during a READ from memory, measured in clock cycles. Side-note is that the memory chips themselves must also support and be programmed for whatever CAS latency is set for READ accesses Here are scope pics showing what you really get for various CAS latencies (READs). The memory was run at 100Mhz (1:2 Divider) to make it easier to see the time delta from CAS to the first data (indicated by the rising edge of DQS after the Read Preamble). Regarding the quality of the signals... this was a quick and dirty session using the "hang-a-wire-instrumentation" method... but you still "get the picture" :

Here's CAS set to 2.5 in the BIOS:


Here's CAS set to 2.0 in the BIOS:


Here's CAS set to "1.5" in the BIOS:


Now AMD processor's also allow you to set a different CAS latency for WRITE accesses. It's Tcwl in the BIOS. Here's a pic showing a Read with CAS=2.0, followed by a Write with Tcwl=1.0:


Nuff said

Peace

[brandinb]

nice job emc2 those graphics are great. i like how you labeled them thats really cool to see what the memory is "doing"
________
M110 ENGINE

[STEvil]

IIRC some P4 boards allowed setting CAS latency to 1... Winbond chips could take it (with some drop in overall overclock), but unsure of others since this was when Samsung TCB3 were pretty popular.

What would be nice is if CAS latencies from 1 to 5 were useable with DDR1 so we could test for an "EB" effect in many different types of chips.

[Eldonko]

Just to put this to bed, so to speak...

CAS latency as normally thought of is the latency from CAS going low till when the first data is available during a READ from memory, measured in clock cycles. Side-note is that the memory chips themselves must also support and be programmed for whatever CAS latency is set for READ accesses Here are scope pics showing what you really get for various CAS latencies (READs). The memory was run at 100Mhz (1:2 Divider) to make it easier to see the time delta from CAS to the first data (indicated by the rising edge of DQS after the Read Preamble). Regarding the quality of the signals... this was a quick and dirty session using the "hang-a-wire-instrumentation" method... but you still "get the picture" :
Nuff said

Peace

Wow thanks for posting that, cool to see how the RAM really works.

[HARDCORECLOCKER]

Just to put this to bed, so to speak...

CAS latency as normally thought of is the latency from CAS going low till when the first data is available during a READ from memory, measured in clock cycles. Side-note is that the memory chips themselves must also support and be programmed for whatever CAS latency is set for READ accesses Here are scope pics showing what you really get for various CAS latencies (READs). The memory was run at 100Mhz (1:2 Divider) to make it easier to see the time delta from CAS to the first data (indicated by the rising edge of DQS after the Read Preamble). Regarding the quality of the signals... this was a quick and dirty session using the "hang-a-wire-instrumentation" method... but you still "get the picture" :

Here's CAS set to 2.5 in the BIOS:


Here's CAS set to 2.0 in the BIOS:


Here's CAS set to "1.5" in the BIOS:


Now AMD processor's also allow you to set a different CAS latency for WRITE accesses. It's Tcwl in the BIOS. Here's a pic showing a Read with CAS=2.0, followed by a Write with Tcwl=1.0:


Nuff said

Peace

Great work !!!

[Der_KHAN]

Here's CAS set to 2.5 in the BIOS:


Here's CAS set to 2.0 in the BIOS:


Here's CAS set to "1.5" in the BIOS:

what about CAS read 1.0 ?

[HARDCORECLOCKER]

UPDATE:

checked the latency with EVEREST - no difference between CAS 1.5 & CAS 2.

[krampak]

So.... this may be the reason that i'm getting higher and more stable clocks at cas 1'5 than at cas 2... at least, I get less memtest errors at 1'5 at the same frequency..

[Der_KHAN]

So.... this may be the reason that i'm getting higher and more stable clocks at cas 1'5 than at cas 2... at least, I get less memtest errors at 1'5 at the same frequency..

i dont get it, whats the reason?

i noticed increased stability with 1.5 too but that wouldnt be possible if 1.5 would be the same as 2.0