I have just completed my first build with an FX-8350 CPU. I'm getting to know the BIOS more, and I was wondering whether it's a good idea to turn on AMD Turbo Core. I've read that it disables some cores and makes the rest work harder. Does it improve performance and can it possibly harm the CPU?
Basically it will underclock/shut down unneeded cores and bump up ones that are in use. However I have seen some anecdotal info that states that there are two stages. Stage 1 is all cores up to a certain frequency (depending on the TDP of the cpu) and the other is half the cores up to max turbo.
What could be causing the problem is this. Lets say that the game takes 4 cores. You have 8 cores and 4 FPUs (which are used in gaming). With turbo on the BIOS senses that only 4 cores are in use. So it shoves everything on to 2 modules, and powers down the other which frees up TDP for pushing the 4 remaining cores faster. since it shuts down a full module, you lose 2 FPU and are down to 2.
When you disable turbo core what happens is that the game sends out a thread for the FPU. You have 4 available so those threads have less time to wait to be processed. So the scheduler utilizes all the resources it can to get the best performance.
I'd say OC the CPU over enabling turbo core. OCing would help utilizing all cores at more speed whereas in turbo, as described above, your CPU will run only certain cores on OC and others will be down.
Turbo Core: will bump up the frequency of your cores, if you have a thermal headroom. There is a circuit on the CPU, which estimates the thermal output based on it's usage, and boosts the core frequencies accordingly. Cool'n'Quiet: if a core is idle, the Operating System (in windows XP you needed a separate software) can reduce the frequency or even park (=shut down, C6 state) the core.
If you are just gaming, these features don't make much difference. If your game produces a light workload (you are looking at the skybox or at the ground), Turbo Core will unnecessarily boost your cores; when stuff happening, you will immediately hit the TPD wall, and your clocks will drop to all-core-boost P state (or even to the base clock, if the game is that demanding).
Cool'n'Quiet was rather clunky in the windowsXP era, and could affect performance; in newer operating systems the scheduler is smart enough to not drop the clocks during gaming.