TO KNOW ABOUT INSTALLATION OF RAM

May be ram slot is damaged ,try to switch and try both rams individually . If required try different rams.

Hello yeah, you can use both RAMs if they are compatible in terms of bus speed and type like DDR1.
Different types of DRAM modules (eg. DDR200 and DDR266 DIMMs/PC100 and PC133 DIMMs) should not be installed on one motherboard at the same time. This motherboard supports memory modules with capacities of 64/128/256/512MB and 1GB.
Hope this helps

two different brands are fine

Try reinserting the RAM into the RAM slots. If you have two RAMs inserted, try switching slots. The RAM can be loose from its slot when moving around frequently.

did u check the old RAM...do they also show only half ?
may be ur new RAMs are not compatible with ur MB
what's the speed of ur new RAMs....400 or 533 ?

actually there is no such fix available as mother board in complete has different component that works in sync and changing bios wont be of much help instead try compatibility chcek and update only the most needed hardware

hi im josh in cebu phils. friend no setting to be modified the problem is in *********** board.it can not detect two memory at a time especially having different value. coz when the memory works it will swap since one of the memory is hgher it will create complications.so to avoid such problem you choose to use the same value of memory in both memory banks. like if youre using 256 of the 1st memory bank use alson 256 for 2nd memory bank. then try to use the same brand for better. good luck!

download express installation for bios update from http://www.updrivers.com/bios/Motherboard/Intel/12/176.html
put on one ram only in windows run your bios express installtion
file

are you sure your acer supports this type of ram ... check out the specs on the website first ... any ram sertting in the BIOS will be under advanced chipset settings ...

1)not all rams are dual compatible 2)did u try both sticks separately? (1 may be damaged) 3)are they exactly the same? CAS, voltage, etc..? Sometimes different CHIPS cause trouble 4)try changing to 333 mhz if it works, go back to 400 and try either CAS 3.0 (assuming auto is 2.5 or lover) if not working yet, try the "T" seeting to "1". If your BIOS doenst show this setting and is AWARD, after getting into it with DEL, press CTRL+F1 and then look which setting came from the dark... (hidden settings) on Gigabyte boards for ex. it has to be done.