Hi! So i bought a pair of Hypertec 40Y7735-HY (2 GB,DDR2 SDRAM,667 MHz, SO DIMM 200-pin) to upgrade my old Macbook Pro early 2008 (Penryn I belieive). So after installing the two new sticks, the computer won't boot. However, when pulling one of the new sticks out replacing it with the old one the computer starts and reads 3 GB of memory. Trying the same setup with the other new stick together with the old stick, same result. I've googled and searched around, and I see similar stories with 800 Mhz incompatible memory, but surely the memory i bought is 667 Mhz, and the work independently. Does anyone have any good advice on this matter (besides of course, don't be a cheap ass and buy more expensive memory ;D)?