May not be worth much but my STe has zero whine, I need to turn up the volume on my speakers really high to hear anything and at such a level I'd blow my speakers if I played something out of the STe.
But your post made me think of something I always found different between my STe and others I've seen posted online. My power supply has two large ferrite rings in it, both at the input of the power into the ST and at the exit of the power supply into the motherboard. Most every other photo I've seen of the ST PSU online doesn't have these for some reason. Since ferrite rings suppress high frequency noise, I'm wondering if this is why my ST is so quiet compared to yours (assuming yours doesn't have the same rings). You can see a photo of mine here: