Then be ready for some crashes on your PC, you can't mine and do video gaming at the same time, not even watching videos on your PC can work, when you mine the miner will use all available CPU and GPU power
Will it affect my GPU/CPU lifespan? Is it necessary to run the desktop 24/7 without shutting down? Just pretty curious.
Sorry to interrupt, but what is the amount you expect to earn while gaming/mining ? I'm far from mining, but I have a feeling, that if you play like 4-6 hours a day, mining cryptocurrency for 4-6 wont bring you much. You wont even recapture costs of electricity spent during playing (if you plan to "play for free"), and chances of killing your hardware a much, much higher than just playing all day long.
Which games people play nowdays? Fornite, PUBG, Dota2, CS:Go, GTA5, some MMORPG probably. These kind of games "eat" lots of resources of your PC, and parallel mining will turn your PC into calculator. Of course you turn graphics on low and play 10-20 FPS, but believe me, you wont get any pleasure or entertainment from it, nor will get any earnings.