Why won't 2 different 2gb DDR3-10600/1333 work together

[gost]

Hello,
what is the difference between a crucial 2GB CT1227194 RAM and CT2342776 modules? I have 2 modules of each 4x2 for 8gb total. I have an acer aspire M3410 PC that came with 2x2gb of one spec above and I tried to add 2 more 2gb modules of the other spec and it would not work even though they are both DDR3 10600/1333mhz spec RAM. Windows resource monitor shows 8gb total but 4gb is for hardware reserve.Windows sees 8gb but only3.99gb is available. It's not the CPU being seated wrongly and I updated to latest BIOS and no memory mapping options in the BIOS either. I also uncheked max memory in msconfig all to no avail.Re-seated all modules and tried all combinations. Need to figure this out. Help is appreciated

 

[gost]

wanted to also mention that when I just install the second 2x2gb modules alone the PC won't boot up and gives a steady beep sound but when I have all 4 sticks in (original 2 with computer and the 2 added on) it will boot and show 8gb but only 3.99 usable and 4gb is hardware reserved. Any clues?

 

[johnmule]

wanted to also mention that when I just install the second 2x2gb modules alone the PC won't boot up and gives a steady beep sound but when I have all 4 sticks in (original 2 with computer and the 2 added on) it will boot and show 8gb but only 3.99 usable and 4gb is hardware reserved. Any clues?

This is easy #1 OS is it Windows 32 bit or 64 bit?
#2 does the MB have 2 or 4 slots for the ram? (when you use only two ram modules the slots matter when using only two)
#3 I am just guessing at this moment based on the info you have mentioned about the 4gb reserved it is a 32 bit system and if it is a 32 bit system you will need a windows 64 bit os to handle 8gb.
#4 not sure on the quote message but your info is telling

 

[gost]

Hello, It's a 64 bit WIN 7 OS with 4 RAM slots on the MB I ended up buying 4 new 2GB PNY sticks and all works fine now. Still wondering why the 2 previous different brands of same spec would not work together.
Thanks

 

[alyoshka]

They didn't work together because of the placement of the RAM sticks.
Usually if I go in series, you have RAM slots 1-2-3-4 on the mobo. When you opened the old rig at that time the RAM (2 x 2Gb) were placed in slots 1-2, 3&4 were empty. You added RAM into slots 3-4 and started the rig. right?
You actually had to remove the old RAM from slot 2 put a new stick in it and put the older RAM in slot 3 and the second new RAM in slot 4.
Now if you ask me why this is, it's simple, it's got something to to with the way these slots are connected, since the models are different , something has to be different and for the rig to be able to strike a balance, you need to give it stuff in equal proportions, that helps the controllers understand what is put where and how much current is required to run it. Plus the timings are set accordingly.

 

[gost]

You are correct! I did alternate the slots and memory with all possible combinations and still no good. Thanks for your response, it is good advice for others to see.