Even without those mods, it's new enough to throttle if it gets too hot, and there is a pretty big buffer before you do serious damage to them due to heat. At any rate, why kill it, it's a fantastic machine for using when you want to try something new or before a major update on your main system.
If you need an excuse to upgrade, how about USB 3 or Type C, Sata3 or even better, NVME, HDMI, Display Port, Thunderbolt, 32GB of ram, MUCH better GPU, longer battery, better wifi, higher res screen with better color calibration... The X220 was an awesome laptop and had this been 3 years ago, fine, but now? It's getting long in the tooth. Really, really long. Honestly, my only concern with upgrading at this point would be the OS if you're using Windows.
Side note,
Win7 currently sits in the mid to high 30% range of Windows market share, once it drops below 30% expect hardware manufacturers to ignore it at exceedingly faster and faster rates even without MS pushing them to. I expect it to cross that mark 1st quarter of 2019 and that doesn't even take into account the holidays which always brings a surge of new systems. Lest you think Win8.1 is safe it's market share is already single digits, it's only saving grace is that it uses the same driver engine as Win10.