what cas latency is best for 2008 macbook pro
The two main facts I have been able to establish are the following: The E5520 is not capable of supporting 1333 ram at its native speed. I have been unable to learn how to increase the memory speed of the -Chipset- to 1333 MB without changing the processors first. 1066 Ram (Currently Apple ram) has a CAS latency of 7-7-7-20 which has the same latency as the 1066 RAM manufactured by OWC Corporation.
CAS latency of 1333 ram is 9-9-9-24 for all the ram I’ve been able to find.
With the intention of replacing the processors in the future, I flashed the bootrom to version 5,1. It should be noted that I am upgrading from 8 GB to 32 GB of ram (and in dire need of more) and I would like (based on what is said here) to buy memory that matches the future processors’ speeds so that I won’t have to consume excessive amounts of memory then. There are ways to check CAS latency of your RAM.
Will the ram downclock ok?
The wider window (1333 vs 1066) offsets the higher latency (21 vs 17).
Has anyone upgraded the ram before the processor with the Boot Rom Flash?
In the other direction (upgraded ram had lower latency, higher clock speed -still downclocked- and wider window), I have seen this sort of latency difference make an observable difference on WinTel boxes (maybe due to window differences?). I haven’t seen any Mac RAM with lower latency for a faster clock speed after all; what gives?
Can RAM be mixed? Read more here
JEDEC compliant RAM
SPD timings for lower clocks will be present if the RAM is JEDEC compliant. The downclock should work fine as long as the vendor is reputable… Based on how they set up the table, it would be better to have tighter timings. It’s likely that without a way to measure or tweak SPD timings on a Mac, you’re stuck with whichever timings are set to ensure maximum compatibility between memory controllers and mainboards. The reason behind this is that if RAM latency is a critical factor to you (more likely than not), you should buy RAM with the tightest CAS latency rating appropriate for the speed at which your system can access the memory.
The latency would be 15ms instead of 11ns if you purchased DDR3-1600 9-9-9, which has CAS latency of 11ns, but programmed it to run at 8-8-8 at 1066, which would result in latency of 15ms. It’s impossible to know before buying, and there’s no way to do so. For best results, you should consider buying RAM with the tightest timings possible (e.g. DDR3-1066 6-6-6 or 7-7-7). It is then that you will be able to determine what you are purchasing. When it comes to RAM latency, memory bus frequencies, and even interleaving channels, it’s probably not much point, as you’d be splitting hairs when it comes to performance.
Read more on 11 Best quad channel ddr4 ram
PC-10600 DDR-3 1333 with the 9-9-9-24 Latency
According to my PC-10600 DDR-3 1333 ram from OWC, all its latency settings are 9-9-9-24, and it has a 21-segment window as well. At first glance, it does appear that the bigger window makes a difference, but I have yet to perform some experiments to confirm this. When I run Geekbench 64 just with the 1333 sticks, I will post the memory performance printouts to show if the difference makes up for the latency.
There has not been an enormous improvement in the numbers, but a noticeable difference has been made by reducing swaps. Strangely, the difference is not noticeable in Windows 7 Pro 64, but it can be measured in OS X! Honestly, I wasn’t expecting that!
Final thoughts on what cas latency is best for 2008 macbook pro
It’s just by chance that since there has been so much talk about Crucial and Corsair memory, I decided to contact them just to make sure: neither of their products have been “certified” as being compatible with OWC’s scanner, and the only memory that they have that might be compatible is more expensive than OWC, and not just by a penny or two either.
Furthermore, I would like to mention that the customer service provided by OWC is beyond anything I have ever encountered and continues to improve every time. I would recommend them simply based on those factors, but there is more to it than that. There was some uncertainty about whether any ram would be able to do the job because there were possibility of future upgrades, which is why both a tech representative and an engineer stepped into the chat room. In order to ensure that the RAM would work with all the plans of the project, they carefully examined my plans and made sure the RAM would match the plans before directing me to the correct location.