Question Ram is not displaying correctly

[CybeR_PunK_69]

so my pc have only 1gb ddr3 1333mhz ram but today i bought a new 2gb ddr3 1600mhz ram and i put both the sticks on my pc ....it booted successfully but in properties it only displaying 1gb ram but in cpu-z app it is showing 3 gb of ram .....whats the problem....if i only plug the 1gb ram stick it displays 1gb both in properties and cpu-z but with both sticks plugged... it displayes 1gb in properties and 3 in cpu-z.....btw my specs are
genuine intel r processor
and hcl pegatron IPM41-d3
no graphic card
sorry for my bad english
thanks in advanced
here is a link of my screenshot

 

[CybeR_PunK_69]

which processor is best for my cpu genuine intel(r) cpu 2140 or pentium 4 currently i am using genuine intel(r) cpu 2140

 

[rgd1101]

https://support.hp.com/us-en/document/c02185182

http://chiplist.com/Intel_Core_2_Duo_E8xxx_series_processor_Wolfdale/tree3f-subsection--2309-/
E8500