How long did you run memtest86+? It must be at least 3 passes in one session, and 8 passes would be better. It would be good to see if memtest86+ finds any errors with the old RAM, because errors can come from CPU, motherboard, RAM slots, etc. It might also be worth running one of the free CPU testers.
Hi all, I needed a laptop so researching on the web I found the possibility of upgrading this model. Some say max RAM is 6GB and others said 8GB, so I bought 2 x 4GB ddr3 1333mhz with a Kingston SSD to. The problem I have is the system recognizes 8GB but only uses 2.93GB. I have tried many solutions, updating BIOS to the latest version, drivers, but could not get the system to use more than 2.93GB. The two ram I bought have the same characteristics as the original ones (2 x 1GB). Well I thank you for any ideas or comments, best regards!  
Inspiron 14 N4030, hardware upgrades