Hi @cus
The type of CPU and ram is determined by what is supported by the motherboard's IO (Input/Output i.e. north bridge/south bridge) chipset.
This IC is the interface between the CPU and the rest of the motherboard.
According to the Dell driver support page for the model, your laptop's motherboard has an Intel GM45 Express chipset. (Type chipset in the driver support page Keyword search box)
The specifications show what types of CPU and ram it supports.
The other thing regarding compatible CPUs is to find one that fits into the same socket as is used on the motherboard. Here's a list of chipset compatible CPUs but you need to make sure that it is a Socket P type CPU so that it will plug in and work.
I have read that the model will support 8GB of ram but it needs to be DDR3L 1066 (PC3L-8500) as anything higher won't work
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