Combining Ram?

Solution
Whenever it is in your power to do so it is always best to keep the RAM the same size and brand.

Mixing will often work provided it's the same specification but why risk winding up being one of those for whom it doesn't.
Whenever it is in your power to do so it is always best to keep the RAM the same size and brand.

Mixing will often work provided it's the same specification but why risk winding up being one of those for whom it doesn't.
 
Solution
Your computer will starting nagging you about how it doesn't feel good, and something is wrong.
If you keep it in there to long you are going to kill it...

Two different voltages isn't a good thing.

Just buy the same brand/type and you'll be fine.