However I didn't find any concrete tests where you could compare the power consumptions in real-world situations
Well this article
compares an E6400 with a P4 631, the E6400 uses less. I realise the P4 has much more L2 cache, but this is just as a comparison. Also later on in the article it says:
A new power management method exists in the Core 2 Duo that allows the processor to accurately manage consumption even in load. This is called, Ultra Fine Grained Power Control. It consists of a very precise cutting out of areas that can be placed in sleep. Non solicited units remain in sleep even if the others run at full speed. This often happens, because itÂ´s rare that all processor units are solicited at the same time. This ultra precise management makes it possible for better control of power consumption and thermal dissipation.
I don't think the Celeron has this.
Also Xbitlabs measured the power consumption of the E6300:http://www.xbitlabs.com/articles/cpu/di ... ent_8.html
However, for the dedicated AMD fans I would like to mention a few facts that may change the attitude to the last chart. The thing is that S&M, just like many other tools creating ultimate processor workloads, use special floating-point operations. And it was fine for CPUs on K8 or NetBurst microarchitecture. However, Core 2 Duo processors do not get loaded to the full extent with these utilities. We had to go through a number of different burn-programs to realize that there are a few old ones that do the job much better than S&M, prime95 and others.
For example, when we resorted to BurnK6 tool that we used to use to heat up AMD K6 processors back in the days, we managed to get much higher power consumption numbers for Core 2 Duo E6300: 55W for the CPU and 229W for the platform. In other words, Intel Core based processors hit the maximum power consumption and heat dissipation in absolutely different type of tasks than their competitors and predecessors.
So it depends what you will use the CPU to do.