When you put 4 GB dd3 pc3 8500 and 4 Gb ddr3 pc3 10600 in motherboard together in HP dv6 with I-3 processor running Windows 7, what happens? Is it acceptable?
Well, at worst it will not work.
DDR3 is better in mixing than older DDR2 is. Make sure it has the same voltage, 1.5V.
In most cases it will work fine. But the best is to match with the same RAM.