Motherboard doesnt recognize all memory slots...

Hello everyone ,
First post here .

I recently bought a motherboard and a processor.
MB: Gigabyte GA-EP41-UD3L GA-EP41-UD3L (rev. 1.0) - GIGABYTE - Product - Motherboard - Overview
CPU : E7400 (Freq:2.8Ghz , FSB 1066 , 3MB cache)

All fine here.
I had home 4x1GB DDR2 667MHZ M378T2953EZ3-CE6 .(Samsung)

In my motherboard i have 4 memorry slots.
If i use any of the those memory in slots 1 and 3 it works (having 2GB).
If i add in slot 2 and slot 4 the other 2 i cant use it , the computer simply enters in a reset loop.
I switch those 4 dimms in all ways and still nothing.only in 1 and 3.
Someone told me that the issue is that the MB was ment for 800Mhz not 667Mhz like my memory.
But if 2 works why not 4?
I made the Bios Update from F4 to F5 ..nothing.
Someone else sugested i should play with the memorry and put it lower the 667 and the computer might see all of these..tried that ...still nothing.
What is odd , is the fact that in Gigabyte memory list they have Samsung that works with DDR2 , 667Mhz but 4GB module.
http://www.gigabyte.com.tw/FileList/...-ep41-ud3l.pdf

If someone has an ideea (exept buying new memory:) ) what to do please tell me.

Thank you ,
Bogdan

as i said : I made the Bios Update from F4 to F5 ..nothing.
Plus all 4x1GB works fine but not all togheter.

thank you .donno if its not soemthing with the freq of what the MB supports..
it might be that i got PC5300 insteand ofPC6400.

i need more that that could be it :) ty anyways very much.

FZ21Z said:

poctanlee said:

thank you .donno if its not soemthing with the freq of what the MB supports..

Perhaps this is why...

Because of Intel chipset limitation, please use single-side memory module if four memory modules are to be installed.

thats very logical, i had a dfi board that only supported low density ram chips had to buy them from america (that was 5 yrs ago)

ok i understand
Thanks guys.