Ok, here is what I managed to do; and it should work fine with others too.
Purchased from the same eBay seller, with 4GB single slot, English+THAI keyboard layout in 40,000 INR [~660USD]
I'm not sure why there's difficulty in upgrading the RAM to 16GB (2x8GB) in DELL Inspiron N5420-V560114TH
On the same day of delivery, I upgraded memory to 2 x Transcend SODIMM DDR3 Synchronous 1333 MHz (JM1333KSH-8G
). (costs 5K INR | 82USD each)
After a month, upgraded to 250GB Samsung SSD (840 EVO-Series / MZ-7TE250BW
) [8K INR / 130USD]
# If anyone interested, here is the complete dump of hardware specification, http://pastebin.com/QS1ycz6K
* I personally didn't like battery life. weight and display quality (so this one is for everyday use and for traveling and all, macbook-air); apart from those things, this outperforms in terms of overall price (58,000 INR / 955 USD).
Hope this helps other users to transform 14" into a powerful beast from within