Yeah 90 degrees (I am assuming celcius) is to hot. I would think that your CPU is throttling there. If Crysis 3 is pushing those kinds of temps you'll certainly want to refrain from running Prime 95 as AVX instructions really heat up Haswell.
I would remove your heatsink and have a look at how well it was seated on the IHS. Of course this will require applying new thermal paste when you re-install it. Since I don't know which exact model heatsink you have, I'll make a guess and say it uses 4 screws for retention. When tightening it, make sure to go in a X pattern and try to turn each screw like one turn each time until they are all tightened. This way you should get even pressure on the face of the IHS.
Also have a check at what your motherboard is pushing for Vcore. I've found that most motherboards when left on Auto, tend to set Vcore too high.
It's true that AMD uses more power (and have lower IPC making them much less efficient), but that doesn't mean that Intel CPU's are going to be cooler. Supposedly Intel improved the TIM used between the IHS and die, but it's still not as good as the solder they used prior to Ivy Bridge. Because the heat transfer is less efficient, the on-die temps remain hotter than AMD's socket temp even though Intel is using less power.