Memory not recognized

Hi guys

So i'm very noob, and this is the first time i upgrade ram memory, i had 2x2 gigs of ddr3 ram at 1300 mhz, and now i took those out and replaced with 8 gigs of a single stick of transcend 2rx8 ddr3 1600 ram, problem is, the bios does not recognized that memory. In fact, i get the blue screen "A problem has been detected and windows has been shutdown...." so windows won't start.

Can't understand why, and btw i'm sure all 4 dimms are woking propely

What motherboard and what OS are you using?
Also you mention 3 DIMM's but you also said 4 in the closing statement, exactly what DIMM's are you using?

mobo is a p7p55 lx, cpu i5 650 3.2ghz, gpu 560 ti. OS windows 7 64 bit.

And i have 4 dimms, all properly working

That motherboard only supported up to 4GB DDR3 DIMM.

Have you tried updating to the latest BIOS as that may support your memory without harming anything otherwise you will need to change to 2 x 4GB.