Well, to be honest, besides what you have done, the only other thing I could recommend is a full re-install of the OS with all the drivers properly installed, 1st chipset, 2nd on-board stuff, 3rd Graphics card...
You can also do this. Use any of the coolers mentioned here that have been said to work. I recommend Zalman's solutions or, if you're short on cash, Arctic Cooling. Also, consider getting a heatsink for the RiAlto chip on the backside of the card (the one that has a pink-ish pad on it, near the AGP connector). That chip gets very hot while gaming and cooling it properly will give your card a longer life-span and will show better results.
Before all that you could just replace the thermal paste on the card's cooler and see if it improves anything. If you don't know how to do it there are several guides in the web, that are very good.
Heres one. It applies to CPUs, but is pretty much the same with GPUs.
Consider that nollo might not the funds to upgrade to a whole new system, something that you sure are proposing. Considering nollo is still using an AGP board it's also safe to assume that he's also still using DDR RAM and a Pentium4/D or an Athlon 64. So after all this he would need to upgrade motherboard, CPU and RAM. Also, to take full advantage of today's technology, most good boards come with a EPS12v connector (i.e. 8-pin +12v board connector), something that his PSU might not have, since old boards only used 4-pin. But get this, there aren't that many games that make use of DX11, yet, and AGP is supported by all current games. So while you are right about the performance increase between PCI-e 2.0 and AGP 8x, if the user only wants a solution to his current issue (properly cooling the card), let's just provide that, shall we?
Not only is it cooler, it also consumes less. As for performance, it's about the same as the HD 3850 AGP up to 1440x900, after that the HD 3850 is better, because of the 256-bit RAM bus length. The HD 4670 also has better support and less performance impact on AAs and AFs up to the mentioned resolution.
Yes, there is.
To fill in your System specs, please,
click here. Don't forget to select "Yes" on the drop-down selection box right in the beginning of the page.