I've had my GA-Z68X-UD4-B3 for well over a year or two with no major issues. I recently had a case fan fail so I replaced all of them at once with two 120mm and one 240mm fan. Previously all three were plugged into a Molex power connector as that's how the case came with the installed fans but the replacements were all 3-pin small connectors and could be plugged into the motherboard (good since I can now see RPM data).
The GA-Z68X-UD4 has two case fan headers and one PWR fan header. I could plug the 240mm fan into a Molex connector and did with the other fans going to the two case fan headers, upper left and lower right.
Well, the Gigabyte board seems to run the front fan header at half speed so the fan is not running at its rated RPM. Took me a while to figure out that seems to be a Gigabyte thing. So I decided to try the fan connected to the PWR fan header and that ran the fan closer to the rated RPM but with one odd thing - the computer boot loops several times before finally booting up completely. Odd. It doesn't do this EVERY time but MOST times. I've tried both fans and one of the older fans but the outcome is the same - plugging in a regular 120mm fan into the PWR fan header causes a boot loop. What's up with that?
So in order to have the front fan run at rated RPM, pull in more air and not boot loop , I have to have a Molex to 3-pin adapter and plug the front fan directly into power. Wile that's not a really big deal it bugs me that the computer boot loops with a standard 12V case fan plugged into that PWR fan header. According to the manual the header is just a regular 12V fan header as far as I can see. There should be nothing special about it.
Anyone know why the computer would boot loop with a regular case fan plugged in there? It's bad enough the front case fan header runs at half speed but the PWR fan header that runs it at full speed causes boot loops....