CAS Latency Questions

apcs13 · Feb 9, 2014

Hello everyone, just as a heads up I have G.Skill Sniper DDR3 1600 RAM, 8GB of it, and my specs are in my signature.

I was just looking in CPU-Z because I am doing an OC stability test for my CPU and I noticed that under the tab "Memory" it says "CAS# Latency (CL) is 11.0, when my memory is supposed to have a CAS Latency of 9.0.

I have two questions:
1. Is this a bad thing and if so, how do I fix it?
2. What exactly IS CAS Latency? I'm not entirely sure on what it means either, and maybe if I knew that I would have a better understanding.

Thank you for any answers and replies!

millwright · Feb 9, 2014

Long story, but I'll try.

The whole number is ie 9 9 9 24

If you add up all the numbers, that is how many clock ticks, it takes that memory to do 1 memory operation.

I can't remember exactly but 1 is finding the info another is how long it takes to turn on that memory section, another is reading it, and so on.

If you overclock 1600 memory to more than 1600 the cas will drop to a higher number.

If you haven't overclocked anything, you may have to set the cas manually, IF your BIOS supports those settings

Edit
So cas9 memory is faster than cas11

millwright · Feb 9, 2014

I was thinking Cas isn't important anymore, now that memory is so fast, but it dose matter in the high end still. Not so much with 1600 memory.
Here is the articlel that changed my mind.
http://www.anandtech.com/show/7364/memory-scaling-on-haswell/3

apcs13 · Feb 9, 2014

Thanks for the replies, do you think you could help me to find the BIOS settings to set the CAS Latency to the correct value? I'm not entirely sure how to do it, and Googling how to surprisingly didn't bring up any answers either. I have the Asus m5a97 R2.0 motherboard with UEFI BIOS. Thanks!

EDIT: I didn't remove this just to make sure I have done it correctly, but I went into the UEFI BIOS and found the DRAM timing controls and it turns out it was set to auto and 11, because when fiddling around with a bus OC earlier my RAM auto-OC'd by mistake, which in turn raised the latency and I guess it never went back down when I reduced the RAM to 1600MHz.

So I changed the first 4 timing slots to 9,9,9, and 24 per the manufacturer's page on Newegg and your suggestion, and now CPU-Z does pick it up properly. Have I done it correctly?

millwright · Feb 9, 2014

It is pretty easy.
I haven't had an Asus board in a while so I can't tell you exactly.

Go in and look around.
When you see it you will know it.
It is usually in the first or second category.
You will see the Cas fully exhibited.
It may have a setting to change it to manual, first.
If the Cas settings are greyed out, then there should be a manual setting.

Your manual usually has a list of all the settings in the BIOS

apcs13 · Feb 9, 2014

millwright :

I'm pretty sure I was able to do it correctly, but I did edit my last post describing how it was done, do you think it sounds about right? I only altered the first 4 settings in the DRAM controls and left all else to what it was before, auto. Thanks

millwright · Feb 9, 2014

Yes, and I was just looking at the Asus BIOS.
What a difference from any BIOS I have seen.
Graphic interface? Talk about easy.

I just put together a new MSI computer 3 weeks ago, and haven't had the time, or desire to even look at the BIOS.
Guess should check it out.

Sounds like you fixed it, and you are welcome.

apcs13 · Feb 9, 2014

Awesome, thanks for the help!

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