Z400 heat sink/fan and bios issues

[david32000]

cleaned cpu fan/heatsink. When reinstalled started getting warnings that the cpu was too big for the cooling syst. Temps are never higher than 50 C, so I just hit F1 and finish booting up.

Tried updating bios to 3.61 Rev A. Machine slowed down and occasionally I have to do a restart before it will boot all the way. Thought I would go back to the earlier bios but see it is not available (just read that it is risky anyway). This new Bios has resulted in the fans running at a constant high speed, no more quiet Z400.

[BeemerBiker]

There are two fans and the high performance fan has jumper from pin1 to pin5

the above is NOT recognized as the high performance

You can replace the fan with any good quality 4 pin fan but you will need to jumper pin 5 of the header to ground or to pin 1 which ever is easier.

[david32000]

The jumper is there, there is however an offset key on the

connector. It can be connected with the jumper floating

or connected. 
When it was working properly it ran at a temp

regulated speed, now it's all or nothing. Have connected

it both ways, one way is full speed, the other it does

not run.

[BeemerBiker]

You might want to read this thread 

https://h30434.www3.hp.com/t5/Business-PCs-Workstations-and-Point-of-Sale-Systems/HP-Z400-Fan-Noise-...

I have the 6 slot version of z400 and at one time used that PWM noise reducer mentioned by @SDH   above.  My system runs 24/7 on CPU intensive tasks so I run the fan at max.  I tried the app "speedfan" but it did not recognized the fans. I suspect you can only set fans performance in the BIOS.

I once had an EVGA liquid cooler for my x5680 but after a year or so the pump blades broke.  The reported speed of the pump was about 5000 rpm but no water moved and I went back to that high performance fan.  Intel CPUs shut down so my xeon never died even with the water not flowing.