Hello,
there is no standrd idle temperature of a CPU. The temperature depens on your room temperature, the CPU's VCore and the cooling you use!
My room temperature for example is about 18-20°C, I use and Thermalright SLK800 Heatsink with a Delta 80mm EHE
[email protected](~2600 RPM), 4 Sunon 42CFM(rating at 12V) Case 80mm case
[email protected] and a 120mm Delta 107CFM(rating at 12V)fan, also @7V.
My idle temperature of my Celeron 1,0 GHz A at 1,33GHz with 1,35V Vcore is about 29-30°C and my full load temp is about 35-36°C!
If you want to passive cool such a Celeron 1,1GHz CPU at it's standard speed, then just keep in mind that you have to lower the VCore to get acceptable temps. For example I can run my Celeorn 1,0 Ghz stable at 1,2V Vcore with very low temps --> it could be passive cooled at that speed and shouldn't exceed temps of approximately 50°C at full load!!! Your idle temp should be about 40°C if you passive cool your Celeron 1,1Ghz @1,2V Vcore, I think.
Good luck with you setup!
Regards
Ingo