Desktop CPU problems?

Hello, first time poster here. Hope I'm not breaking any rules. So I own an Alienware Aurora R4 that I bought 6-7 years ago, overtime I upgraded a few part with the help of geek squad ( I know they dont really know what they're doing, I just have no clue either). But recently I've been getting a few issues, such as: * computer very slow, until I deleted a bunch of games (harddrive was only half filled before delete). * Sometimes, when turning on. Monitor, keyboard, mouse wouldnt react. * Computer freezes with looping sounds, while gaming. My guess is that I need a new CPU, as some websites listed that as the cause of many of problems, and I havent upgraded it at since I got this pc. Does that sound right ? Here is some of my specs what more would I need to add?, as well as my system info . (https://i.imgur.com/mK9ddpk.png) * GTX 980 * Intel Core i7-3820 CPU 3.6GHz * Alienware™ 875 Watt Multi-GPU

Again, sorry if I broke any rules/bad formatting.