Strange memory issue

[alacarde]

Hopefully somebody here can think of a known memory issue that applies to my situation. Thanks in advance. So heres the deal:

 

When I attempt to use a corsair value select memory stick I get a beeping noise and the computer refuses to even turn on.

 

I have a proMos Technologies memory stick with the specs:

512MB

DDR 400

CAS 3

unbuffered

non-ECC

64M x 64M

part# v826664k24sctg

 

Also I have a Corsair Value select memory stick with the specs:

512MB

DDR 400

CAS 3

unbuffered

non-ECC

64M x 64M

part# VS512MB400C3

 

The proMos works in a dell dimension 2400, while the Corsair does not.

 

FYI:

PC is a dell dimension 2400

Bios is updated

Dell Bios does not allow you to change memory timings

Dell Bios does not allow you to change voltage settings

I have tried the memory in all motherboard memory slots

The memory DOES work in another of my PCs

I have tried booting with both memory sticks in and the computer will start. However, only 512MB of memory shows up in the BIOS and Windows.

 

Specs for the proMos:(last one on page)

http://www.promos.com.tw/website/eng/product_data.jsp?grup=g2

 

Specs for the Corsair:(track with part #VS512MB400C3)

http://www.corsairmemory.com/corsair/valueselect.html

 

Configurator:

http://www.corsairmemory.com/corsair/configurator_search_results.html

manually type in dimension 2400

 

The configurator shows that standard corsair memory is compatible, but it does not say the Value select is compatible.

 

Anyone have a clue what the difference is?

 

Thanks for your time.