Almost nothing, those processors are a offer and I put in mayuscules that I want only one of this two cpus...I know they are very very old
If I understand well, the E5800 is only better by the higher clock speed, which means that the C2D E7300 will performs a lot better if we put them to a same clock? I mean, overclock the E7300 to 3.2Ghz
I say this because the E7300 is better in all aspect except the clock speed
That's correct. The E5800 has a higher clock speed, but the E7300 has more cache and more instruction sets enabled. Other than that they are physically identical.