I'm running a machine that's a few years old now. On the whole it works well, but my hobby is music production/songwriting and some of the software is starting to leave the machine behind. I don't think it's quite ready for retirement.
The processor is an Intel Core Quad Q6600 2.4 mhz,
The motherboard is an ASUS P5 Q3 Deluxe (Wifi edition) which I believe has an LGA775 socket. There is a list of compatible processors on the ASUS web site, but I'm not that technically conversant to understand what all the different options mean. I feel confident enough to tinker with the BIOS if anyone things overclocking it might be an option, but again I'm not completely sure a) what that means and b) if it would do any good.
The operating system is Win 7 Pro 64 bit.
Does anyone know if there a viable upgrade that would be worthwhile?
The best you can do is to retire the machine.
Or, you must abide by the list of supported processors asus has.
Note that any upgrade processor must be socket, chipset, AND BIOS compatible.
You can use https://ark.intel.com/ Intel® Product Specifications to look at specifications/features and compare processors, from the list of supported processors from asus.
And, you have just over a year of support remaining on Windows 7.
So, I would plan for the future.