Mixing RAM sticks?

[It's Not Lupus]

I want to purchase another stick of RAM, but I'm too cheap to buy the same kind since it's no longer on sale.

Is it OK add another RAM stick to a rig if it's a different brand but with the same specs? What about different specs (speed, timing, cas latency, other)? What are the possible issues?

 

[ArisVer]

They may or may not work together. You might end up having a useless stick. In general it is bad practice especially with dual channel memory.

 

[alkemyst]

I mixed two brands and by themselves they have faster timings, when mixed they go to slower settings. Also make sure both use the same voltages.

 

[maxi007]

if same model its ohk else chk frequency , voltage
else it will end up with 1 stick damage

 

[BonzaiDuck]

What alchemist reports makes sense.

I've used Corsair, Crucial, OCZ and G.SKILL, and always in pairs.

On one LGA-775 system we have with an eVGA 780i motherboard, I wanted to double the RAM to 8GB.

It initially had a pair of G.SKILL "Black Pi" DDR2-900 modules running at 850. I had a spare pair of G.SKILL DDR2-1000 modules.

The JEDEC SPD specs showed the RAM kits overlapped voltage and timing specs at DDR2-800, so . . . . that's what I did.

Given the way I build systems, I wouldn't even bother to mix manufactures, even if the particular system used low-end parts otherwise.

My sig system is running DDR3-1866 2x8GB G.SKILLs -- Ripjaws Z. I have a pair of good Ripjaws 2x4GB modules of DDR3-1600.

Since the spec timings and voltage of the kits are identical at the respective speeds, I'm quite sure I could run them for 24GB of RAM at 1600.

But why would I bother? 16GB is plenty. Waaay plenty.

 

[ikachu]

If you mix DIMMs with different timings, the BIOS will attempt to pick the fastest common settings (i.e. settings supported by both DIMMs). This may be significantly slower than the fastest setting for each DIMM on its own.

If you mix DIMMs of different sizes, it can affect interleaving (one of the tricks that is done to improve throughput and utilization) so you will probably end up with one interleaved region of memory (the size of the smaller DIMM x2) and one non-interleaved region the size of the remainder of the larger DIMM. This probably doesn't have a huge performance effect though.