Plz recommend a CPU only for 15K with wireless Keyboard & mouse

[gobble]

^^ err I would not recommend that, coz that blocks the upgrade path .... with one stick, you always have slots available for upgrade, else with two 2x2GB if you want to upgrade to say 16 GB you would have no option except to forfeit your sticks

dual channel memory access can speed up access for reads and writes done seperately. Why lay waste an important part of the system architecture?
RAM is not too expensive, after 2 years when it it is time to upgrade, you can get 16GB for the same price as 4GB.

--G0bble