So this is probably a noob question but anyways 
My motherboard is an Asus P5k LGA775.
I currently have 2 sticks of 1gb RAM in the black slots:
If I put one of them into one of the yellow slots the PC doesn't start up, not even to BIOS.
This is the RAM I currently have in the PC:

Someone has donated 3 sticks of RAM to me but they don't fit in the slots even though they told me they are also DDR2.
They gave me 2 of these:

and one of these:

Are they the wrong type of RAM or are those yellow slots just not meant to be used?
My motherboard is an Asus P5k LGA775.
I currently have 2 sticks of 1gb RAM in the black slots:
If I put one of them into one of the yellow slots the PC doesn't start up, not even to BIOS.
This is the RAM I currently have in the PC:
Someone has donated 3 sticks of RAM to me but they don't fit in the slots even though they told me they are also DDR2.
They gave me 2 of these:
and one of these:
Are they the wrong type of RAM or are those yellow slots just not meant to be used?