There are a few CPUs out there, which are impractical for Monero due to several circumstances, but can be used for Aeon. I'll pick two examples.
1.) AMD Jaguar/Puma based APUs, e.g. Kabini, Beema, Carrizo-L. These APUs have 4 cores and support for AES, so would be usable for cryptonight coins like Monero. But they have no L3 cache and a shared L2 cache of just 2 MB. With Monero, one single thread fills the last level cache (in this case L2) completely. So 3/4 of the computing power would be unused.
A way out could be Aeon with its cryptonight-lite algorithm. Here, the dataset per thread is only 1 MB (if the miner is configured right) and you can use two cores till the LLC is filled. In case of xmrig, you have to setup:
algo = cryptonight-lite (the algo for Aeon)
av = 1 (stay at a dataset size of 1 MB and don't double it like the auto-config does)
threads = 2 (use two threads to use the compute power and fill the L2)
Configured like this the 15W $299 notebook APU AMD A6-7310 hashes 182 H/s for Aeon
2.) A similar case is the latest Bulldozer based APU codenamed Bristol Ridge. Here AMD has reduced the L2 cache per module from 2 MB to 1 MB, which is
insufficient for Monero. In addition to that the L2 is not shared for all cores like Jaguar's, but dedicated for each module (=1 FPU + 2 ALUs). So the config from above can be reused:
algo = cryptonight-lite
av = 1
threads = 2
But a
dditionally we have to ensure, that the two threads stay in their own module since the two L2s are private. So we have to add
cpu-affinity = 0xA (in Windows version of xmrig)
Configured like this, a Quad-Core (2 modules) Bristol Ridge AMD A8-9600 can reach 345 H/s with Aeon. That is not great – the predecessor Kaveri is much more powerful with Monero and Aeon – but better than nothing