Ive seen questions about the Touchsmart 300 and replacing the cpu. I have a HP Touchsmart 300 - 1040a - a 2009 model - and have upgraded not only the cpu but also increased the memory and installed a 1Tb SSD. The memory and SSD is no problems. HP specs say only 8Gb ( 2x4Gb) memory can be installed, but it will take 16Gb ( 2x 8GB ). Even though the bios shows only 8Gb, it does accept the 16Gb RAM. The CPU i installed is an AMD Athlon 605e - AD605EHDK42GM - C3 chip. The original bios will only accept a C2 chip. HP released a bios update in 2011 i believe that accepts the C3 chip cpu. If you are in the process of upgrading your Touchsmart, i suggest you go to the HP website and download all the latest drivers and firmware for your system for a hassle free installation. My Touchsmart has served me well for the last 10 years but with continued updates to Windows 10, it has been getting slower and slower. With these new components i installed it is again super fast, and will last me another 10 years. I hope this helps anyone else doing the same.