I don't have any first-hand experience with them, but I'm skeptical. So is "Dan" at "dansdata.com". Read
it here, if nothing more than to get a chuckle, Dan's a funny guy. His measurements of stressed RAM showed a 1 (one) degree celsius increase above ambient. This was without a heatsink. He admitted his measurements could be off, and guessed the could have been waaay off and there was actually a 5 degree delta. But that's nothing to worry about.