Amd 9500GT quadcore + geforce 8500gt

I wish I could help you out man but I don't know a whole lot about that specific CPU and graphics card.

For overclocking my graphics, I normally use MSI Afterburner. It doesn't allow upping the voltage most of the time, but you can adjust the core clock and memory clock. Typically with MSI Afterburner you can adjust it to the MAX and your GPU will be fine. I wouldn't worry too much about overclocking the graphics memory though. It doesn't help performance really at all and sometimes causes stability issues. So definitely try that. It'll probably work.

Another program for Nvidia cards is Nvidia Inspector. Sometimes that'll allow you to overclock. You can also try EVGA's program if you have an EVGA version of a Nvidia card it works GREAT. It also works if it's not an EVGA version sometimes.

As for the CPU. I don't know if that CPU requires a BCLK increase or a Multiplier increase. On my computer I just have to adjust the multiplier and the Vcore voltage. However, on yours you may have to adjust the BCLK and the Vcore voltage. Or a little of both. I would first try to search online for what to adjust on that specific CPU. Then go from there. Typically you can overclock a little without having to adjust the voltage at all. So if you don't want to do any research I would say just adjust the multiplier by .2-.3Ghz. If stock it's 20, then go up to 22 and see if your PC will boot. If it doesn't then bump up your Vcore voltage a little. If your Vcore is normally 1.15, go up to 1.2. If that doesn't work then go back to stock. Then try to adjust your BCLK by 2-3. If it's 100 stock. Go to 102 or 103 and see if it'll boot. If that doesn't work try upping your voltage a little. If nothing will get you to boot into Windows then you'll have to do some research.

Well, I hope this helps you out a little. I see no one here's answered your question so I figured I would try and give you the best answer I could come up with. That's a shame too because I know someone here knows a lot more about your PC than I do.