That actually makes a lot of sense -I know that Notebook Hardware Controls used to take care of this magnificently on Windows XP... I'm having a hard time finding a working version of it (or something like it) for Windows Vista 64 bit though
Hey, yeah. As I suggested you could try and check your Vista Powerconfigs and find the values that control your cpu... Put everything to 100% there and you SHOULD be fine, although I'm not so sure about it. You could try
http://cpu.rightmark.org/ (Rightmark CPUClocktool); it can do pretty much the same things as NHC, but is a bit harder to use. I'm not sure it works on 64bit, but give it a shot (like you did with the newest amdgpuclocktool ^^.
Also, I use pretty much default settings on CCC and try to apply filters and stuff from ingame... I've noticed some games get very, very bad fps if you enable Narrow or wide-tent antialiasing instead of box. (Hell, even the Chess game in Vista started to stutter)...
I don't know why your card locks up past 600mhz, but mine makes 681mhz without artifacts; anything higher gives random artifacts and anything higher than ~710mhz makes the card crash on heavy load (e.g. in good looking games
) You might also wanna check if there is no background activity, like Windows Defender or what not, hogging your CPU and HDD.
Good luck.
P.S. I use the old AMDGPUClocktool (v0.7) because for some reason, either using ATITool or the new AMDGPUClocktool makes the card run really hot and disables powerplay until reboot... I've also had the 0.9.8 crash my pc for no apparent reason (for instance while just opening to program to check the temps), so I'm sticking to 0.7.