That's a tough one to reason out.
To be honest: Not meaning to bash HP tech support or anything (they're only doing their jobs), but you're not likely to get a reply about anything going outside the initially posted technical bounds of their machines. It's a tech support thing. If they start telling people "Yeah, it's not officially posted, but it WILL do this" it will only lead to more headaches than they NORMALLY have. I don't blame them, even if it's somewhat inconvenient to the tech-savvy amongst us. I once e-mailed them asking about my DV9700 and whether it would support Intel VT-x if I replaced my C2D T5750 with a VT-x supporting chip. Their response was: "No, it will not. If the option does not show up in the BIOS, replacing the CPU will not help. You would need to buy a new computer with that feature already enabled."
By doing some quick research on their own site, you can find a few spots where it's pretty clear that VT-x is a BIOS feature that shows up ONLY when a VT-x supporting chip is present. I do not blame them for their reply, they're adhering to printed documentation and, of course,trying to make sales. I replaced my T5750 with a T7250 and lo, I had VT-x.
I also replaced my 4 GB (2x2) DDR2 RAM in the system with 8 GB (4x2) as an experiment, and that also worked. This despite HP, Intel, and Crucial's websites ALL insisting that the chipset on my board supported a max of only 4 GB.
The moral? With the price of 8 GB DDR3 RAM sticks dropping fast, I would honestly try it out as an experiment. Even if it DOESN'T work, you can always resell the sticks or potentially refund them.
On a side note: People can correct me if I am out and out wrong, but the memory controller in modern systems is a part of the CPU and NOT the NB chip. The NB should have NO bearing on how much RAM your system will support. This has been the case for several years now, longer for AMD than for Intel even. As an example: I have a Core i7-2630QM in my DV7-4296NR. The max RAM HP and Crucial list for the system is 8 GB. However, CURRENT systems are sold with an i7-2630QM and 16 GB, so I would assume mine will run it as well. I have not had the chance to try this yet, but planned to after next paycheck.
That being said, if you can find instances of running a Phenom II N620 or similar with 16 GB, then you have a good chance of it working for you, too.
I hope this information is useful for you in some way. Like QHN said: If you try it out, give us a shout and let us know how it went. Always good to know where rules can be broken!
O Shadow Fox O