https://www.pcworld.com/article/1936128/the-6-biggest-pc-hardware-myths-exposed.htmlTL:DR (Opinions are of PCWorld only)
1. Are dedicated sound cards better than integrated ones? Only if you are listening to something of high quality, WITH high quality sound hardware. Otherwise you cannot tell the difference.
2. Will more RAM make your PC faster? Only if you didn't have enough to begin with.
3. Is a long HDMI cable bad for quality? Only if the cable is bad or if it is TRULY long (50 feet+).
4. Does a higher clock mean the CPU will be faster? Only if
everything else about the processor is identical.
(As a teen at a friend's house, his father (an Intel employee) had a new computer with Intel's first quad-core. The computer was noticeably faster. When I asked if this was because of the cores, he responded, "No, Windows doesn't know what to do with the extra cores yet. It's because of the double-size L2 caches." Processors share the L2 cache, and the cores that were working were benefitting from the extra cache allocated because of the cores that were idle.)5. Does overclocking damage the hardware? Not if you don't tell the software to ignore the safety parameters, which is will avoid by default.
6. Does shutting down the computer by cutting the power damage the hardware? No, but you run the risk of losing data and needing to reinstall Windows.