I need help I am planning to upgrade RAM on my laptop. I don\'t even know if my laptop can handle it. I am experiencing that my current RAM almost reach its max capacity! I need an upgrade TODAY.

Specs:
Lenovo z480

-Intel Core i7 3612QM @ 2.10GHz Ivy Bridge 22nm Technology
-4.00GB Single-Channel DDR3 @ 798MHz (11-11-11-28)
-LENOVO Lenovo (CPU Socket - U3E1)

I am planning to buy 2x 4gig with higher frequency than I currently have. I made a canvass last time and the only available ones for laptops are 1333mhz and 1600mhz. I think I will be good with 1333mhz do you think my laptop mobo can handle it?

I need it for Soft Dev (Java Android, Visual Studio, playing video games when stressed etc.), and multiple applications opened at once. I will be considering HDD upgrade too but that could wait. I just desperately need RAM.

What is the best RAM upgrade regardless of the brand? My budget is around 4k. Need advise. TIA!