Ram upgrade cas 9 or 10

Raptor26

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Nov 15, 2014
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Hello, I'm upgrading my ram from 8gb 1600 (2x4) to 16gb 1866 (2x8). But, I don't know if I should get cas 9 or 10? What is the benefit from one to the other?

 
Solution
The basic difference between CAS levels in a nutshell (and a very general way).

Think of the CAS latency as the wait period between executing instructions. Between executing two reads for example, the memory controller has to wait a number of clock cycles between instructions, so the higher the CAS, the slower it is because it has to wait a little longer. Normally, when you have two memory chips of equal mhz, ie: both 1866mhz. The one with a lower CAS will, in general, be a little faster. It gets a little trickier when you have different mhz speeds AND different CAS levels, and the general way to figure out which one is faster is:

Divide the MHZ by the CAS. The higher the result, the faster the ram.

So - if you have a 1600mhz...

Rookie_MIB

Distinguished
The basic difference between CAS levels in a nutshell (and a very general way).

Think of the CAS latency as the wait period between executing instructions. Between executing two reads for example, the memory controller has to wait a number of clock cycles between instructions, so the higher the CAS, the slower it is because it has to wait a little longer. Normally, when you have two memory chips of equal mhz, ie: both 1866mhz. The one with a lower CAS will, in general, be a little faster. It gets a little trickier when you have different mhz speeds AND different CAS levels, and the general way to figure out which one is faster is:

Divide the MHZ by the CAS. The higher the result, the faster the ram.

So - if you have a 1600mhz CAS 7, and an 1866 CAS 9, which is faster?

1600/7 = 228
1866/9 = 207

So technically, the 1600mhz CAS 7 sticks are -faster- than the 1866 CAS 9. Whenever you're comparing RAM sticks, this is the best way to judge the potential of any RAM. Now, this won't automatically translate into a faster computer as there are numerous things which affect complete speed (HDD drive or SSD? Fast processor or slower processor?) the whole point is that it expresses a potential for getting things done faster since you're running quicker RAM.

This is especially important in AMD APU scenarios, or any CPU which is relying on integrated graphics as the IGP utilizes system RAM for graphics, and the faster the RAM the better the graphics will run.

Of course, this all has to balance with price, you don't always want to chase the lowest CAS regardless of price, but it gives you a way to compare value.

So, in general, given equal mhz speeds, lower cas is better. Given different mhz, divide the mhz by the cas to get a way to rank the ram by speed, then divide by cost to find the best value. Got it? :)
 
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