2GB+4GB RAM not working

[tableton]

Greetings all.

I am looking for a solution to my problem. My parents have an ACER ASPIRE X3900

Original Specs:
530 Intel Core i3
3 GB DDR3 (3X1GB sticks)
500GB
310 512mb nvidia Geforce

This computer has been lying around unused (in working condition!) and I decided to upgrade the RAM for better computing. So I opened the unit and discovered that there was a single 2GB DDR3 RAM (1333 Mhz transcend). It was changed by my dad when the computer starting giving some issues. So, I picked up a 4GB (1333Mhz/Transcend) to compliment this. Since then, I have encountered the following

a. irql_not_less_or_equal error
b. Bad Pool Header
c. The screen freezes on "Acer Empower people". There are options to enter boot setup (DEL and F12), but they don't work.

Here's what I've tried
1. Tried using the 4GB stick alone.
2. Used both the sticks
3. Used the 2GB RAM (this option alone works)

My question:
1. Will this combination work ? If so, what do I need to do.
2. Instead of 2gb+4gb will I need to try a 2X4gb option ??
3. There are 2 blue slots and 2 white slots in the mobo. Is there a particular order/color code to be used ?

Thanks !

 

[Tradesman1]

What's the 4GB model #, I'm guessing it's a newer model (Since 2011 or so) which is made with high density memory ICs which the mobo doesn't like, best I've found for older boards like yours are the older GSkill NT series of value DRAM which was made with low density ICs (chips)

 

[tableton]

Hi Tradesman1

The model no. is Transcend TS512MLK64V3H