2 Memory sticks won't work together.

[GhandiInstinct]

The motherboard is a P4VXMS.

I'm using 2 PC100 512 sticks, they work individually but together the system doesn't boot up.

Any help?

 

[Jiggz]

If these are PC100 there is a probability the mobo cannot handle this ram density type or more than 1 stick. Do you have a 256mb stick to try?

 

[GhandiInstinct]

The motherboard supports 1.5gb which would be 512 per slot. Are you referring to 8 chip or 16 chip modules when you speak of density?