trying to upgrade RAM in Probook 6550b

[mikeh420]

Trying to upgrade memory in a Probook 6550b. Do both modules have to be the same size, or can I add a 4GB module to the existing 2GB module? Not sure if that's the problem, the laptop keeps rebooting after adding the 4Gb module. Even if I install the 4Gb by itself in the main slot under the keyboard, it keep rebooting. I'm trying both Hynix HMT451S6DFR8A (4GB 1Rx8 PC3L - 12800S) and Kingston KNWMX1-ETBS15476KU4X (same specs as the first).

Thanx

[Huffer]

The 6550b and other HP notebooks with the 1st gen Intel Core processors are very finicky about memory. I pulled up an image of both the 4 gig modules you are trying and both are high density (4 black blocks on the side of the RAM module). These models demand low density memory, 8 black blocks on the side for modules larger than 2 gigs. 

I sometimes see people get away with 2 x 2 of high density and have even been shown that HP shipped the laptop with 2 gigs of the high density, but we have answered dozens of inquiries from people who run into a brick wall trying to upgrade to 6 or 8 gigs using high density modules. If you install a low density 4 gig module I can pretty well assure you it will work. 

Also you really want to use 1.5 volt memory not 1.35 volt. While all 1.35 volt can also run at 1.5 volt it is not ideal. The laptop is designed to run DDR3-1333 1.5 volt low density SO-DIMM modules up to 2 x 4 gig for 8 gigs total. 

Post back with any further questions. 

[mikeh420]

Thanks for the quick reply. Haven't had problems with chip density since the DDR1 days, didn't know it still was an issue.

[Huffer]

Only on the 1st gens...