Temp one is a temperature at some point on the motherboard, I think the Northbridge, not the CPU temp. The only temperature you should look at for the CPU is the core which is at 35-40, quite a nice temp. I believe that this chip can handle at least 70C, but I am not certain.
Before doing any hardware changes, I would check and see if Speedfan is indeed showing the right temps.
I read elsewhere that a good way to test is to stress your system for ~10 minutes, then reboot quickly and find your system temps in BIOS, see if they are anything like what they were in Speedfan. Try this at some point and let me know.
53c should be fine as a maximum temp. My temp 1 usually shows 45 at idle and can get as high as 52 when doing video rendering. If your Northbridge doesn't get much higher than this, you should be fine, but if you are concerned, you can try mounting a fan. Most motherboards can facilitate this, and have a dedicated fan header (NBfan), but you should have a look for a guide on your motherboard or chipset to make sure.