Distilled water is not non-conductive, it's just less conductive than regular tap water. In any case, water (whether distilled or not) is also a universal solvent. So, if there is anything conductive in your loop (like copper, for example) you can be sure it will end up in the water eventually, lowering it's resistance. But anyways, that's awesome that you've had good results so far and haven't destroyed anyone's system yet. You're obviously willing to take a calculated risk that I wouldn't take, especially with someone else's hardware involved.
By the way, I did see that motherboard submerged in a fish tank full of mineral oil thing. A cool idea, but a novelty at best. The actual results from that little experiment wasn't any better than a decent air-cooling setup from what I remember. That system wasn't even a high end gaming system. The whole thing was more of a proof of concept than anything else and has no real practical application.
By the way, I did see that motherboard submerged in a fish tank full of mineral oil thing. A cool idea, but a novelty at best. The actual results from that little experiment wasn't any better than a decent air-cooling setup from what I remember. That system wasn't even a high end gaming system. The whole thing was more of a proof of concept than anything else and has no real practical application.