@punkncat yeah. I just mentioned a 2500k as the bare minimum. Of course, if the OP can afford better than that, then he should buy something better.
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going into a bit more detail why I said it's impossible to upgrade the OP's potato pc for Hitman 2...
because I too have an lga 775 potato here in the house (it is semi retired, and mostly for data storage). For fun, and to keep the old thing going.. I gave it multiple upgrades... cpu upgraded from e8400 to q9500, added an SSD as main drive, upgraded HD5450 to GTX 1650, changed the aged power supply to brand new Seasonic, installed Windows 10. With all these combined it became some sort of raging animal (lol) capable of playing less demanding Playstation games like Xenon Racer at 1080p full screen without lag. It also became capable of playing Genshin Impact, no lag at medium setting, V-sync off.
But despite all these... an lga 775 is simply not enough for the more demanding games. Don't have Hitman 2, but I do have Black Tail which has similar requirements. You can see in the video, I had to settle for 720p, and even that is barely playable.
Xenon Racer is at 4:55
Black Tail is at 18:29
View: https://youtu.be/k2jMHaJggG4
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so even if by some effort, the OP manage to do the same multiple upgrades... it won't be an enjoyable experience playing Hitman 2 in his lga 775. Better for him to just buy another pc if want to play games like Hitman 2.