Nossmayo - you seem correct. If it boots with stick A , but not with Stick B then I'd suggest stick B is knackered. Memory mapping management is some bios option that you _might_ need to use to 'see' all 4 Gigs in Bios.
BTW, @shauncr91 It's not a concept of 'half a stick of ram', it's a limitation of a 32Bit operating system.
A 32 Bit operating system can only address 4Gig's of memory. Sadly this 4Gig includes graphics, sound, ports etc and then Ram. Therefore, if you have a 512Mb GFX card you'll probably only see 3.25 gig of Ram in Windows.
The Solution is to use a 64 Bit OS, for example Vista 64. (Windows XP 64 had SERIOUS lack of drivers so stay away).
Happy to help.
BTW, @shauncr91 It's not a concept of 'half a stick of ram', it's a limitation of a 32Bit operating system.
A 32 Bit operating system can only address 4Gig's of memory. Sadly this 4Gig includes graphics, sound, ports etc and then Ram. Therefore, if you have a 512Mb GFX card you'll probably only see 3.25 gig of Ram in Windows.
The Solution is to use a 64 Bit OS, for example Vista 64. (Windows XP 64 had SERIOUS lack of drivers so stay away).
Happy to help.