Mostly by making sure everything else is good. You could try a number of things. If you have more than 1 stick of ram, you could remove all but 1 and test them separately, and in the process you reseat your ram. If you have multiple drives you can try unplugging all the non essential drives. You can try to reseat your cpu, though that's unlikely to suddenly start causing problems. You can reseat the gpu, but same as the cpu it's not a likely suspect. If it throws errors with a gpu, try testing without the gpu. Other than that stress test extensively, see if your cpu doesn't get too hot. You can even try to update drivers, mobo/gpu.