Computer doesn't boot all the way unless system fans are connected to the mobo

[tracerit]

I just got a new case (Lian Li A05B) and the two 120mm fans included aren't as quiet as I'd like them to be. So I tried to turn the computer on with those fans unconnected but it didn't boot. Once I connected one of the fans (3pin on the motherboard), then it would boot.

When I had everything in my old case, I had a 120mm exhaust fan connected to the 4pin power connector (from the PSU) and nothing connected to the 3pin on the motherboard. It still worked.

Any ideas as to what's going on? My motherboard is a Gigabyte P35-DS3L.

 

[JustaGeek]

Disable "Fan Monitoring" in BIOS.

But make sure that your fans, especially the CPU fan, are working properly, or you risk frying your processor.

 

[tracerit]

I just switched those two 120mm fans from a 3pin connector to a 4pin power connector and it works. I don't have any option to turn off fan monitoring, only one to disable smart FAN control but that only throttles the CPU fan to max speed which is even louder.

 

[JustaGeek]

Whatever you do, especially with the Smart Fan enabled, watch your temperatures closely - especially the CPU temp.

Good luck!

 

[tracerit]

Yeah, I have Speed Fan installed and the temp is steady at 42C.

I haven't solved anything yet though, since my goal is to get the system to run without those system fans connected just to see how quiet my system can be.

 

[JustaGeek]

It is either airflow, required to cool the components - or the killer heat.

Keep the airflow going - at least a large exhaust fan in the back (120mm +, 1200RPM +), CPU HSF, and I would recommend at least one bottom front intake fan (80mm, 1200RPM, to keep the negative pressure inside the case, and fresh air supply)

 

[tracerit]

it's definitely not airflow. i've tested after turning the computer on and off and changing the connection of the fans within a minute.

 

[JustaGeek]

Originally posted by: tracerit
it's definitely not airflow. i've tested after turning the computer on and off and changing the connection of the fans within a minute.

I meant that you either keep the steady airflow inside the case, or you risk damage to the components from the heat.

The price of silence, IMO. I do not even believe in those "silent" Video Cards, or "Fanless" CPU coolers.

The heat MUST be expelled outside the case - period. Otherwise, you don't have a computer - you have an oven.