The video mode switch on the Asus card I have does pretty much the same thing because both modes have a different BIOS. I decided just to put both cards back to their original settings and overclock instead, especially since I'm not getting consistent shader stats on the older card. Strange how the newest card unlocked with no problem. You'd think that the ability to unlock these cards would've been impossible by now.
Ha funny you should say that, i bought a sapphire [cheapest 6950 i could find 2gb]few weeks back , its definately the lower end but not a bad card anyhow, it flashes no worries but i decided it wasnt worth the risk so i flashed back to original, it has the switch and ive heard that many folks can unlock these sapphire 6950,s[its the dirt 3 edition but without the game included]
First thing i did though, was to redoo the thermal paste and lap the copper heatsink, instantly 3-5c cooler just from that, its almost summer here getting hot ambients up to 30c but it still idles at 35-39c most days, doesnt go over 55-60c under full load,
and it plays all my games at full specs pretty easy, bit of oc, and bobs your uncle!!