Even the HP Maintenance and service guide http://h10032.www1.hp.com/ctg/Manual/c01035566.pdf suggests that 2 Gb is the max. We have several small Acer desktops at work with the same processor and face the same limitation. Sadly this is a pretty old machine, designed for Windows XP. You might see some good performance boost if you swapped the original hard disk for an SSD drive, but beyond that, this laptop is from an era of low hardware requirements relative to today.
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