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Tyler McAdams · Jan 31, 2005, 02:48 AM

I've been looking to see if I could find what speed my cas timing is at in OS X but I don't see it in the system profiler. Is it possible to see in OS X?

Big Mac · Jan 31, 2005, 04:47 AM

Yeah, I see CAS ratings in my System Profiler on my iBook and I'm 95% it's on my G5, too, although I'm not in front of it right now. My iBook's built-in RAM does not have a rating. You don't have a Speed column for your RAM?

Tyler McAdams · Jan 31, 2005, 04:30 PM

It says Speed: PC133-333

Damn! that's my cas rating...? no wonder I did not recgnize it... it's slow as ****

Sophus · Feb 3, 2005, 06:27 AM

Originally posted by Tyler McAdams:
It says Speed: PC133-333

Damn! that's my cas rating...? no wonder I did not recgnize it... it's slow as ****

Funny!
Well, FWIW , I dont see CAS timing either...

Tyler McAdams · Feb 3, 2005, 07:35 AM

What I'm worried about is if I go buy 3 sticks of 222 pc133, will open firmware recognise the new sticks as 222 or will i need to tweak something... anybody?

Cadaver · Feb 3, 2005, 08:29 AM

AFAIK, the Mac's firmware will read/use the default timings directly from the RAM modules. If the modules default to 2-2-2, then I believe it will use them. If the modules are simply capable of 2-2-2, but default to something slower in their SPD codes, then I believe you're SOL.

Don't forget that CAS timings default to use the slowest of any module in the system, so make sure all modules are matched for the same fast timings, otherwise the faster RAM will be run at the speed of the slowest module.

However, on a 100-133MHz (PC-133) memory bus, I personally doubt that faster CAS timings will make any real-world performance difference. BUT, we're all geeks... so tweak away!

FYI: I don't believe there is any (easy) way to manually change CAS timings on the Mac, unlike in many PC's BIOS. There may be a way to program CAS timings via Open Firmware, but unless you know exactly what you're doing, there is a very real possibility of damaging your machine.

Tyler McAdams · Feb 3, 2005, 10:10 AM

Don't forget that CAS timings default to use the slowest of any module in the system, so make sure all modules are matched for the same fast timings, otherwise the faster RAM will be run at the speed of the slowest module.

That's what I had heard. I think I'm going to pick up some P133 - 222 Micron sticks over at OWC. $99.00 a stick is not that bad.

P · Feb 3, 2005, 01:03 PM

Originally posted by Cadaver:
AFAIK, the Mac's firmware will read/use the default timings directly from the RAM modules. If the modules default to 2-2-2, then I believe it will use them. If the modules are simply capable of 2-2-2, but default to something slower in their SPD codes, then I believe you're SOL.

Yes you are. But then that's the correct way to handle latency.

Originally posted by Cadaver:
However, on a 100-133MHz (PC-133) memory bus, I personally doubt that faster CAS timings will make any real-world performance difference. BUT, we're all geeks... so tweak away!

Depends on your cache configuration. With big L2 and L3 caches, it doesn't really matter, because then memory is mainly used when streming a lot of data and latency isn't that important. With smaller caches, a larger part of memory access is random access where latency is more important. It does help a little bit.

Kristoff · Feb 3, 2005, 02:22 PM

It's a waste of your money.

Read what CAS is before you waste your money.

you will never in a million years be able to discern the performance difference between 1 clock cycle delay for the column access strobe, since it's largely immaterial anymore anyway.

Tyler McAdams · Feb 3, 2005, 06:14 PM

Originally posted by Kristoff:
It's a waste of your money.

Read what CAS is before you waste your money.

you will never in a million years be able to discern the performance difference between 1 clock cycle delay for the column access strobe, since it's largely immaterial anymore anyway.

I do know what cas is... but $300 dollars for 3 sticks of ram is a "damn site" less than a new computer.

Kristoff · Feb 3, 2005, 07:09 PM

Changing your RAM from 333 to 222 CAS latency isn't going make your computer perform any faster. If you need more RAM, then get it, but don't replace good ram in hopes of realizing some sort of performance gain. In reality, get a couple 10,000 RPM hard disks and RAID 0 those things, and you'll be smoking.

Tyler McAdams · Feb 3, 2005, 07:48 PM

Originally posted by Kristoff:
Changing your RAM from 333 to 222 CAS latency isn't going make your computer perform any faster. If you need more RAM, then get it, but don't replace good ram in hopes of realizing some sort of performance gain. In reality, get a couple 10,000 RPM hard disks and RAID 0 those things, and you'll be smoking.

Good call... indeed I am going to get a few 10k sata drives in my system... along with hardware raid:

http://www.macgurus.com/productpages/RAID/SyncRAID.php