AMD offers cheaper CPUs than Intel for performance; when it comes to a budget, AMD is often the way to go. AMD has a good deal of CPUs under $100, but we picked the best of them (which are unsurprisingly close to $100).
The Best AMD CPU under $100 has a tie for the Phenom ii x4 965(Deneb) and the A8-3850(Llano(not Liano)).
The Phenom ii generally has higher performance when it comes to just the CPU portion.
However, the A8 has an excellent iGP that is the equivalent of a $60 GPU. When you take this into account, if you are going for a cheaper rig, and don’t intend on getting a discrete GPU, the A8 is a great deal. Despite AMD’s claims for an assymetrical crossfire with a discrete GPU, some tests have shown that having both can lower the score from the discrete GPU.
The Phenom ii is generally faster on tests like Super Pi 32m, where the CPU is used to calculate 32 million digits of pi. The Phenom is compatible with the newer motherboards (AM3+) as it was originally for AM3.
The A8 however, uses the FM1 socket and is not compatible with most of the other AMD motherboards. The FM1 motherboards tend to be rather cheap, though.
In conclusion, if you are looking to buy a value CPU for under $100, your best options are the Phenom ii x4 965 and the A8-3850. If you are going for a more performance rig with a discrete GPU, you may want to opt for the Phenom; if you are trying to save money and won’t get a discrete GPU, you probably would want the A8-3850.