Memory upgrade problem

[Leosco]

I own an HP COMPAQ CQ61-312SA which has as standard 2 x 1GB sodimm DDR2 PC 6400 modules.
I have purchased 2 x 2GB - PC6300/6400- 800 MHZ DDR2, When I installed this upgrade my laptop fails to load even the start up sequence.

What am I doing wrong?

 

[PaulJ]

Are any lights on, flashing or otherwise? Does it beep?

have you tried going through the troubleshooting for the laptop?

hxxp://h10032.www1.hp.com/ctg/Manual/c02114796.pdf

 

[alexstone]

Chack hardware compability first