This is a new build for me. I have an Asus P8z68v-pro gen3 mobo and was attempting to connect 1 of three case fans to the mobo (the other two are connected to the PSU and work fine). I connected the molex to a 4 pin adapter so i could plug it into the mobo. The mobo did not like this fan being plugged into it. Once plugged in, I started the computer and the mobo would not work. The fans wouldn't spin either. I tried this 3 times and on the third time there was a puff of smoke and a flash on the mobo near the cha-1 pins where I had connected the fan. I quickly shut down the computer and disconnected the fan. There is a small circuit near the cha-1 pin that looks to be burned, but the computer starts up just fine and I'm able to play games/surf the net etc. I've been monitoring the gpu & cpu and both are doing fine and working as they should. Everything seems to be working including my other two case fans as well as the cpu fan....just can't get the third to work and I'm incredibly concerned about the mobo after this. My question...do I need to replace the mobo even though everything seems to be working fine? Any idea what would have caused the burn on the mobo? I'm thinking of getting a molex adaptor to plug the 3rd fan directly into the psu...is this dangerous?
I would see about returning the MoBo via an RMA. Could be the fan connector at the board was defective. It may not have been any thing you did. If it was my board I would want it replaced. Contact Asus support and explain to them that you plugged a fan into the socket and it smoked on start up. Also that the same fan works perfectly when powered at other locations. I bet they will rma it for replacement.
I would inspect the 3rd fan for any signs of loose wires or miswiring. Compare it to the other working fans. If it looks normal then yeah, it's actually preferable to hook your case fans into the PSU so go ahead and do that. Sounds like you got lucky with your motherboard. Unless you notice stability problems, you should be fine.
Thanks for the thoughts guys. I have a follow up question though...the fan has two molex leads coming out of it. One is for LED lights which has a male plug and fits into the psu. The other, which controls the fan motor, is a femal plug and therefore does not connect to the psu. I can't find an adapter anywhere...am I missing something? Do I need to find a male to male molex adapter to connect this fan to my psu?