On my 5870s, I get close to 400 at 900/300Mhz (see my post above). With overclocking I meant going above 900MHz and at higher voltages than AMDOverdriveCtrl allows me to. For me it seems to be not much more than 10% gain, and I doubt I want to risk my hardware for that. It would also require a BIOS flash, which may not be entirely without risk either.