Too many variables - motherboard/BIOS default voltages etc will play a factor, as will ambient temperatures in the room.
I would think 38-41'C is a bit on the high side if truly 'idle' (ie no Windows update etc), but ~10'C above ambient temps would be a reasonable jumping off point in most situations.
Unless your ambient temp is ~30'C or your motherboard is defaulting to high voltage, it probably sounds a little on the high side.
All that being said, idle temperatures don't really matter at all. What matters is load temperatures, which you can establish by running stress-tests (and with liquid cooling, you want to run those tests for 20-30 minutes, generally to let temperatures reach a steady state).
thank you Barty1884, I have already ran the stress test using intel extreme utility for a 20 min the maximum Temp doesn't passed 68C , according to the CPU characteristics the max load Temp is 77 "without overclocking" but also it should be 30C in idle state so any suggestion?
77 load, 30'C idle, in what conditions? Where are you quoting this information from?
If it's in XTu, that's going to be 'under perfect conditions'.
Intel well only ever state safe operating temperatures (well, 'max safe' in terms of before throttling) as that's a hard stop. Idle is irrelevant, and subject to too many variables.
30'C idle doesn't sound too out of place, in a ~20'C ambient room
My suggestion would be to take those quoted numbers with a pinch of salt. Without knowing your specific setup, no piece of software (nor individual for that matter) can tell you your idle temps should be X or Y in an objective sense.
Again, if you're within ~10'C of ambient temps, it sounds perfectly normal.