Perhaps my T5 HO fixtures are somehow different, but my 6-tube ones get really, really hot and produce so much intense light that I had to move them all 3' away from orchids. Otherwise, some of the orchids were getting sunburned. I use a combination of 4500K and 6500K in those fixtures. Regular T5 and T8 fixtures produce very little heat but the lumens produced are much less than the HO fixtures.
