Old RAM with new? Not working.

My friend's computer is a HP Pavilion a134On. It came with a stick of 1GB PC-4200 DDR2 (533) memory. He just bought another stick of ram to go with it. Only difference is that it's 667 mhz. Shouldn't these two be compatible and just run at the speed of the slower chip? They aren't working together. BIOS only says there's 1GB of memory despite both modules being in the two slots. If I take out the new one, the old one is still recognized. If I take out the old one, the new one is still recognized. I did this for both slots. Both slots work and both modules work, just both modules don't work together. Why is this? Is there anything I can do to get the computer to see them both??

Mixing ram is a hit or a miss....Looks like this combo won't work.

I also find OEM boxes to be far more temperamental to mixing RAM types. I've seen this with Dell boxes in here in the office.

Mmmm thought I saw this earlier while browsing wiki answer/yahoo answers ....

http://answers.yahoo.com/question/in...1181607AAo0i5l


Anyway you dont mention whether its a laptop or desktop. Some desktops will lower the higher rated ram to 533Mhz, however it's an OEM machine. Dell and HP are the biggest pains in the arse in this sector and usually dont have systems compatible with multiple types of ram.

Laptops tend to have even less compatibility, so that's why I asked.


Also be aware of HP's demented mentality to bios locking. Ive had this before with HP machines. They lock the hardware in the bios so you cant exchange the wi-fi card, install extra ram, etc, regardless of operating system used.

This was a massive headahce for me in the past as well.