Can't find a SODIMM DDR3 1866mhz 4gb kit

[Mansive]

I'm thinking about upgrading my laptop's memory from 2GB 1333mhz to 4GB (2x2GB) 1866mhz, so I decided to google for it.
After searching through numerous brands for 10-20 minutes, I didn't find a single one.

I was looking for a 1866mhz 4GB kit specifically because I've read several articles about how APU's run faster with dual-channel memory and higher RAM speeds. I can't buy a 8GB kit because of my budget.

If there's such a thing, can you guys link me to it?
If not, which of these would give me the better performance in gaming?
A 4GB 1866mhz stick, or a 4GB(2x2gb) 1600mhz kit?

Specs:
HP Pavilion dv6-6b/c Laptop
AMD A8-3520M APU
2GB 1333mhz

 

[Archaic59]

The A8-3520M features an integrated dual-channel memory controller with support for DDR3(L)-1333 memory.

http://www.notebookcheck.net/AMD-A-Series-A8-3520M-Notebook-Processor.61300.0.html

 

[scout_03]

check if this is your system http://www.crucial.com/usa/en/compatible-upgrade-for//hp-pavilion-dv6-6b-c-%28amd-ddr3%29

 

[Mansive]

The A8-3520M features an integrated dual-channel memory controller with support for DDR3(L)-1333 memory.

http://www.notebookcheck.net/AMD-A-Series-A8-3520M-Notebook-Processor.61300.0.html

What does that even do?

check if this is your system http://www.crucial.com/usa/en/compatible-upgrade-for//hp-pavilion-dv6-6b-c-%28amd-ddr3%29

Yeah that's my system

 

[Archaic59]

Memory controller manages flow of data to and from memory. Yours only supports DDR3L-1333 as far as I can tell. The "L" after the 1333 means "low" voltage. Most laptops use low voltage to help increase battery life.

 

[Mansive]

So what does that mean in my situation?

 

[Archaic59]

So what does that mean in my situation?

Buy the same thing that came with it.

 

[Mansive]

So what does that mean in my situation?

Buy the same thing that came with it.

Can you clarify please

 

[Archaic59]

Buy DDR3L-1333 memory. Max amount of memory you can use depends on the motherboard, but it's probably safe to double it to 4Gb. Check your owners manual or HP website support to find out max amount of memory you can use.

here's link to pdf. Memory is on page 66. Shows 1,2,4,8GB with part numbers.
http://www.hp.com/ctg/Manual/c02842252.pdf