Hello..
The Siglent SPD3303X-E laboratory power supply arrived today. What can I say ... I'm verry happy.
The Siglent power supply is super quiet. In addition to Rigol DP321 power supply, you can now work relaxed
and even listen to music

I just don't understand why the Rigol DP831 power supply is so loud after being switched on

After switching on, the fan starts up and then constantly at medium speed.
Perhaps the power transistors in the power supply are "preheated" like in the diesel before the start

Conclusion: Although the Rigol DP831 power supply compared to the Siglent laboratory power supply more adjustment
and Possesses analysis functions (even a system temperature display), I will ultimately
opt for the Siglent laboratory power supply and send the other one back.
Greetings Rolf