Upgrading my RAM (4GB -> 8GB). Please help me understand this..

Single channel mode occurs when only one module is used, OR, when two or more modules are used BUT their memory characteristics are just a bit too dissimilar to allow dual channel mode.

Single channel mode operates at 64 bit memory data width.

Dual channel mode occurs when two or more modules are used with at least one module in one channel, and at least another modules in the other channel, AND, the module memory characteristics have to be similar to enable dual channel operation.

Dual channel mode operates at 128 bit memory data width, and requires at least two memory slots with one slot for one channel, and the other slot for the other channel.

This laptop has two slots. One slot for one channel, and the other slot for the other channel. So this laptop can run either in single or in dual channel memory mode.




Apparently the maximum memory supported by this laptop is 8 GB. This appears to be primarily due to limitation imposed by the BIOS, as the CPU (memory controller) can support up to 32 GB.




Overclocking usually adjusts several primary memory timings including CAS latency. However, this laptop is not capable of (manual) overclocking due to limitations of the BIOS.




The laptop should support either 1.35 V or 1.5 V modules without any issue (provided the memory is otherwise compatible with the system). Lower voltage means less power loss, less heat and potentially longer component lifespan.




Memory bandwidth is usually expressed in terms of MB/s (Mega Bytes per second). And is equal to MT/s x 64 bit ÷ 8. For example memory operating at 1600 MT/s will have a bandwidth of 1600 MT/s x 64 bit ÷ 8 = 1600 MT/s x 8 = 12800 MB/s.

If using new memory which operates at the same frequency as the original memory, then the bandwidth should remain the same. But if (new) memory operates in dual channel mode, then the memory bandwidth will become - 1600 MT/s x 128 bit ÷ 8 = 1600 MT/s x 16 = 25600 MB/s.

And the proposed Crucial memory replacement ^ is compatible with this laptop, by the way, so there shouldn't be any issues.




MHz relates to the frequency of system operation, and usually means the frequency of the clock signal being sent to the memory modules.

MT/s means the number of data transfers per second. For the DDR3 (Double Data Rate) memory being used here, the number of data transfers per second = clock frequency x 2 (because memory operates at twice the memory clock frequency). For example, the memory clock runs at 800 MHz, then the MT/s = 800 MHz x 2 = 1600 MT/s.