For anyone who's interested; I've forked the radeonvolt project and made some cosmetic changes to the code. Well, one functional change in that the program isn't restricted to the HD5850 anymore. It should accept all ATI cards and check to see if the correct VRM chip is in use, and try to proceed if it is.
Also, the subvendor (XFX/ASUS/Sapphire etc.) is now displayed with the device information, and a --debug option has been added that prints out extra (more or less necessary) information.
Github pageI'm still trying to find out if GPU-Z can read the VRM temperatures of my card, because if it is, it should be doable in Linux too.
I have an XFX 5830 that it would be neat to be able to use radeonvolt on, and an asus 5870 (Which I expect less, as I know it is a super-special voltage regulator), and asus/HIS/HIS iceq-x 6870's. Let me know if there is any test info I can provide from them :p
I'd like to point out that I have added no extra features with regards to overvolting capability, mainly because I have no idea how to do it.
At the moment, from the research I have done, it seems like every card that uses the uPI uP6213 VRM controller chip is definitely not overvoltable throught software, and probably not even probable through software (reading voltages, temperatures).
I know the XFX 5870 card I have has a uPI uP6213 VRM controller chip, and radeonvolt reports the following the error when trying to access its VRM controller chip (like many others have reported):
Unsupported i2c device (1a)
As far as I can tell, the value 1a here, is an ID of the VRM chip (0a is the Volterra VT1165). If this indeed is the case, this means that when radeonvolt reports the above error (with device ID 1a), the card in question has the aforementioned uPI uP6213 VRM controller, which seemingly isn't available via software. But I'm not 100% sure of this yet, so I haven't programmed it into radeonvolt yet (ie. reporting "Unsupported VRM: uPI uP6213" instead of the above message).