Thinkpads Forum

Hello Guys & Girls,

I just purchased a T530 (2394-D48) machine and I want to upgrade the machine to 16 GB. I went to Crucial's website and I see two 16 GB packages (two 8 GB Modules in one package). Which one should I purchase or does it not matter? I have provided the two links below for the two 16 GB packages. I am hoping to do 3D modeling and to use MATLAB on the machine.

http://www.crucial.com/usa/en/thinkpad-t530/CT3291588

http://www.crucial.com/usa/en/thinkpad-t530/CT3438420

Thank you again,
John

The CT3291588 is rated for PC3-12800 (1600Mhz). The CT3438420 is rated for PC3-14900 (1866Mhz). All things being equal (i.e., price), I'd opt for the faster PC3-14900 module. However, as of now, it's $20 more than the slower, but still usable PC3-12800. If the $20 isn't a major dealbreaker for you, then buying the faster memory offers two benefits: 1) it will operate at the laptop's PC3-12800 speed and therefore should in theory operate more reliably (you won't be pushing it to the maximum speed that it could attain), and 2) it offers some small protection for future-proofing in that if you obtain another laptop which requires PC3-14900, then you can use them there.

Hi Ray,

Thank you for responding back to me and letting me your thoughts on my question. I will get the CT3438420 which is rated for PC3-14900 (1866Mhz). I did not know that if you went with a higher frequency, it would operate more reliably then PC3-12800. Also, great idea if ever I want to move the memory to a machine that requires PC3-14900 memory.

Thank you again Sir.

Have a great day, Ray!

John

JohnD. wrote:I did not know that if you went with a higher frequency, it would operate more reliably then PC3-12800

Specifically, what does it mean "operate more reliably"

I've used the 1600Mhz and it runs just fine. Never had any issues.

Isn't the 1866Mhz just slightly mo faster?

It's my opinion (with many years spent as a memory test engineer) that if you install a memory module that is spec'ed to operate faster than what the computer system actually runs at, then you will be providing yourself with an operational "cushion". In almost all cases, the faster module will have a corresponding faster data access time than the "slower" spec'ed module; in rare cases, the timings are equal. Thus, when operated at the slower system timing, you are allowing more time for the memory to fetch the data and present it on the data bus. My understanding is that Thinkpads cannot dynamically change their system memory bus speed; it's always locked to a certain timing spec so putting in a "fast" module will cause it to slow down and operate according to what the laptop has.

Think of it this way: let's equate that PC3-14900 (1866Mhz) memory to an automobile engine that has a tachometer redline at 18,660RPM. This is the maximum recommended limit that the factory says you can operate the engine at and still have a reliable piece of machinery. You run it at that redline for days and days. Sure it's sucking gas like crazy and throwing off a bunch of heat. But there's no major problems because it's been designed and tested to run at that rate. Yet, statistically, there is still a very small chance that you could have a fuel delivery problem or a cylinder mis-fire and the engine will sputter and you will encounter a slight loss of power. Now ease up on the throttle so that the engine is running at only 16,000RPM (i.e., PC3-12800 spec of 1600Mhz). It will probably use less gas as it doesn't have to work as hard as before. It probably runs a little bit cooler too. Wouldn't you say that the engine now has a better chance at avoiding a mis-fire or that it would probably have a longer lifetime because you aren't running it at the max? I'm not saying that the memory wears out like an engine but heat is one of the things that can degrade a semiconductor chip over time.

That's what I was thinking

All I know is that I have been running 1600Mhz memory and have never had any issues... that I know of.

Ray, thank you for the detailed explanation and the analogy. It was clear and very understandable. You are a very knowable person.

Rockrz, thank you for asking the question that you did.

John