RAM for my T400s

[MrJimBeam]

Hi

I have a T400s 2808-CYG.
I'm out looking for more RAM, and have found:

KINGSTON HYPERX 8GB (2X4GB) DDR3 1600 NON-ECC CL9 SODIMM (KHX1600C9S3K2/8G)

Can I use them, when there are at 1600MHz.

/
MrJimBeam

[MrJimBeam]

Hi again

Can I use new RAM whit 1600 MHz when the standard RAM are at 1066 MHz

/ MrJimBeam

[rkawakami]

The speed rating (i.e., 1066Mhz vs. 1600Mhz) is not the real issue. What's important is the CAS latency (CL) number. From what I can tell, the typical CL for PC3-8500 DDR3, what the T400s requires, is CL7. You would need a PC3-12800 DDR3 module that has maximum CL of 10. Since what you are describing for the Kingston module is CL9, then it should work. See the "JEDEC Standard Modules" chart at this page:

http://en.wikipedia.org/wiki/DDR3_SDRAM

However, I would still only buy that module as long as the seller accepts returns for incompatibility. There's a special memory chip on the module that contains the timing conditions that the module can accept. If it does not contain a valid mode for CL7, operating at the lower clock frequency of 1066Mhz, then the module may not work.