can i add PC3L with PC3 ram

The following site has a good description of RAM. I assume tyou are tallking abour DDR3 and DDR3L RAM. As the post states DDR3 runs at 1.5v and DDR3L is dual voltage running at either 1.5v or 1.35. So yes it should work fine in your system as long as your current RAM is DDR3. Also since you have either a generation 2 or 3 processor, that makes it fine. 4th generation Intel processors will only work with DDR3L. Just make sure you get RAM that is the same speed. Better would be buying a matched set.

https://www.dell.com/support/article/ca/en/cadhs1/sln153768/what-is-ddr3l-memory-?lang=en

Crucial offers a wide selection of RAM compatible with your system. Try the following site.

http://www.crucial.com/usa/en/memory/crucial

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@ejn63 wrote:

In general, mixing RAM of different voltages is not a good idea.  It may work - but it may produce stability problems.  If you have 1.5 V DDR3, either add that to the system, or replace both modules with DDR3L RAM.

 

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so it's Recommend to have the both rams PC3, to avoid any stability bugs.

True or both DDR3L. That way you are certain to have compatible RAM.