The reason for asking for everything that changed was to try and minimize causes. If, say, you changed only the CPU or CPU plus motherboard, and the prior stuff ran well below what you have now, you could (nearly) rule out things like local conditions, case airflow, etc.
If you changed case, then a lot of airflow things change as a result. What happens if you test other games? Benchmarks? Programs/uses that load many cores highly? You're going to need to test out a lot of other games and programs to try and get a more accurate picture; one game and virus/malware program isn't enough. You need to find out if this warrants contacting the shop about it, and the sooner, the better.
Usually when I do a quick scan with Security Essentials, they are, well... quick and I don't notice any performance impact, so I never thought much of them. I just started a full scan to see how heavy it is (I do have a game, largely a single threaded one, going too). Though, unless we're comparing the same program, I guess this is a pointless comparison, but in my case, it does load my CPU about as much as a game would. My ambient/room temperature is a bit warmer than yours too.
So I'd do more checking to see what the overall landscape is like. You need to establish if the game you tried with half the temperature result was a light outlier, or if the scan was. If you're getting 10C (or more) lower in most other cases and the 90C+ is rare, I'd say it's probably not cause for concern on a stock cooler that isn't that close to throttling, but if you're closer to throttling, you might have airflow or cooling issues somewhere.