what ram module/configuration to choose?

GreatMaster

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Jun 25, 2011
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Hi,
i have been a few days ago gifted with a new laptop:
http://www.clevo.com.tw/en/products/prodinfo_2.asp?productid=467
or more precisely
http://mysn.eu/xmg-p504

it came with 4gb module of this ram:
http://www.crucial.com/usa/en/memory-ddr3/ct51264bf160b

as u might assume that is not too much and i am thinking to upgrade my system.
so i am indecise of what to choose.
i was thinking to buy 2x http://www.crucial.com/usa/en/memory-ddr3/ct102464bf160b
from here: http://www.amazon.com/Crucial-PC3-12800-204-Pin-Notebook-CT102464BF160B/dp/B006YG8X9Y

but in this case do i need to also buy additional 4gb ram? that is i put (8gb+4gb) on one channel and the same amount on the other channel... or that is not necessary?

or should i buy 4 gb and 8 gb and install 4gb on the channel where i have already 4gb and put 8 gb in the other channel?

some people recomended me to throw away what i have and buy a vengeance ram, but i dont know what to do, so i came here to see what the others are thinking.

so can smb tell me what is the best sollution for my case?

i thank u in advance for the answer