The increases are possible especially at the point where the chip is seeing massive efficiency drops, and voltage is now converting to heat at a higher rate via leakage. TPU may have hit/passed that point with their particular sample.
I took a look at Guru3d's article, and while by no means definitive they are seeing that at 4.0 Ghz, the total system wattage is 273W at full load with a 5870 card:
Phenom II X6 1055T and 1090T review
What bothers me most, is that they are seeing a 1090T that is only hitting 44 celsius at 4.1Ghz. Very surprising with a crappy Vendetta cooler, compared to the Scythe Katana used by TPU, that was hitting in the 70s. It may be that TPU just gave it too much voltage. I have to read it again at another time.
So yeah it's possible, but without TPU providing numbers at a lower OC, it may be more an anomaly than real world.