Tested: The DV2315NR can take the 4GB DDR2 800Mhz and work at 800Mhz.

The DV2315NR was a variant of the DV2000 that came with na 1.6Ghz Turion 64x2 and 2x512MB DDR2 533Mhz.

Just registering this info here.
All I wanted was to give the DV2315NR some overtime, be abel to use Windows 8 fast and keep it for a little longer. So:

On eBay I bought
- New 2x2GB DDR2 800Mhz ETECH brand (~$60)
- A used Turion 64X2 TL-60 2.0Ghz 65nm (Max speed with the same TDP, 35W, same socket, ~$7, yes 7 dollars)
- A new SATAIII SanDisk Ultra Plus SSD 128GB (~$110)

I disassembled pretty much all the machine except the screen. Started by removing the battery and everything on the little screwed covers. Took me like an hour to get to the processor. Had to clean sink and the cooler and use new thermal paste. I also took some time to put a copper coin over the nvidia chipset (by its side) and kept it distant from the processor's heat sink, since mine has always been getting very hot.

I kept the screws separeted by area so I wouldn't mix them and put them back wrongly. Was very carefull the the conectors since I had to disconnect a few, like speakers, mousepad, keyboard, etc. Even the 3V BIOS battery had to be replaced, used some soldering for that.

Result was:
The chipset really does takes over the 2GB limit mentioned by HP at the time the laptop was released, and it does gets to the 4GB running at 800Mhz, which is also over the 667Mhz limit mentioned by HP.
The F39 BIOS recognized the SSD, all the memory and the processor instantly.
The SSD transfer rates were not too satisfying but got to around 250MB/s which is over 3X the speed of the original harddrive.

Got Windows 8 64bits fully working, it detected almost everything by itself, Sound, Network, Wireless, useless Modem, SD Card Reader. I had to install a Chipset driver to cover a device called "Coprocessor" and used the Vista 64 driver. The video driver was the most problematic to find, but apparently Microsoft figured it out and made some Windows 7 update the fixes it:

http://download.windowsupdate.com/msdownload/update/driver/drvs/2010/08/20376210_70a476ede1c3a23125e47bfbeb0d33acec9c13b7.cab

Now my DV2315NR boots in like 5 seconds and loads websites on a blink of an eye, I set the video memory on the BIOS to the maximum (128MB) and even the games from Windows Store are working like a charm.

I think It will last for over 3 years without getting anoying.
It discracts me to do this kind of work, so that's why it didn't bother me to waste some time on this thing.