first off you need to know what you have there. please.
is it a QUAD CORE? 40p and 40w both have i7 quad cores as an option. and the memory needs match or better the speed of your processor. (not stated)
back in , 2010 i5 or i7, (520M or 820QM?) (the Q is quad)
there are 2 slot mobo and 4 slot main boards.
the 2 slot is 8GB max. and 4slot 15GB max. (im running 12,NOW)
the memory purchase here are tricky. limited buy i5 or i7 mem, manager, not HP.its and Intel limit. (it connect directly is why)
the next limit is the memory must be 1.35v rated.
i have 3 of these laptops build from piece parts cheap.... (retired tech)
don't be fooled, i have this old (nice) 2gb Samsung stick that is 1.5v
and runs great until it gets warm and fails memtest86, as it slows, from heat. and is just a waste of time, it is the wrong memory here.
the 2GB sticks are easy, and many work, 1.35v or dual voltage sticks.
but not the 4gb, and 8gb sticks are not supported at all.
HP has no spec page on sticks, so use intels. (HP sells memory only that works)
the only 4GB sticks that work are ones with 16chips called low density.
again 1.35v sticks.
put them in in pairs on the i7 quad core.
on the i5 with 2 SO-dimm slots only 2x 4gb is max.
now the topology rules cleary stated in the intel data sheet.
(this is all anyone has)
can i have external links, or will you kick me off here like forum-seven did.
there are no ads on page, or cash collected.
see that matrix chart here.
for 4g. you need 16 chips, 8 front and 8 back
if you go to the store like BB, they have high density memory that will not work, with this old processor
but wait , these do.
Samsung (see these old sticks 2010)
most modern memory fails here.
it says, not to make statements on opinion.
wow. that is rich.!
HP has no spec. sorry that is A FACT.
and intels is 5 years old. now, almost 6.
and they DO NOT REVISE spec's on 5 year old processors to match modern memory
leaving what?, OPINIONS and my testing...
this is complex, but not as bad as overheating, that i cured.
Getting the right memory is not trivial.
cheers and good luck.