Question : Problem: DDR2-800 RAM Kit

Experts,

I installed a 4GB RAM kit on a Dell Vostro 420.  The kit is a 4GB Corsair TWIN2X4096-6400C5 (i.e. 2x2GB DDR2-800, PC2-6400):

http://www.newegg.com/Product/Product.aspx?Item=N82E16820145184&Tpk=twin2x4096-6400c5

The memory specs of the computer are:
dual channel DDR2-800
max 4GB
four slots (2 pair) -- the kit uses slots 1 and 2 (slots 3 and 4 are empty).

Here's the thing -- CPU-Z v1.49 reports:
single channel memory
400MHz DRAM freq.
FSB freq 1330MHz
Core freq 1995MHz

The CPU is: Intel Core2 Duo E8400 3GHz.

WinXP Pro 32-bit is reporting 3GB of RAM... this is normal.

Shouldn't the memory be running at 800MHz instead of 400MHz ?

Why does CPU-Z report 400Mhz RAM freq ?

Why does CPU-Z report "single channel" when the memory is "dual channel" ?

Could there be a problem with the memory, or with the way it's configured ?

Thanks.

Answer : Problem: DDR2-800 RAM Kit

>> What if the Vostro 420 manual is wrong (again), and the upper limit is 8G, but you won't see it unless you're running a 64-bit OS ?

If the motherboard supports more than 4 Gb it may be seeable by a 32 bit OS if the right extensions are built into the motherboard.  Some of the Intel motherboards have what is PAE extensions which enable support of more than 4 Gb for 32 bit OSes.

Now as to what your mother board can support; a similar question came up elsewhere on EE.  The recommended answer was to contact Dell sales support and check with them.