Ok. I'm back with full report. First of all I have to say that I am absolutely astonished by my merom t7200. With rm clockmark I achieved 1.000V at 2.0 GHZ rock solid running 2 PRIME simultanously. It's amazing how that lowers your power consuption. I went forward and found out that it's also stable at 0.950V runnig at 1.8GHz, which I decided was best, cause temperature of both cores, while under FIRE, don't exceeds junction temperature (100 celzium), and therefore TDP keeps frequencies at maximum at all times.
Here is a good example. If I ran one prime that put one core at maximum load at 2.0ghz 1.188V, waited few seconds for a temperature get close to junction temperature and then run superPI 1MB, it calcullated 38 s, which is awful for a core 2 duo. But when I switched to 2.0Ghz 1.000V, ran one prime and one superPI 1MB, it calculated in 27s. If I run only one superPI 1MB with no additional arson, I get 25.5s. Slower times in first example are due to TDP regulating lower frequencies while under load, not to exceed junction temperature and therefore keeping your sistem safe from burning up.
The sounds of silence, brushed my ear-drums.
Gigabyte G33m-DS2R, E4500, 2x1 GB DDR2 800, 500 GB HD501LJ, 7600gt