I can get a Dual core AMD 4600+
And I want to use Linux
but with AMD there is a small problem with timing is some games and game libs/ engines
The AMD Dual-Core Optimizer can help improve some PC gaming video performance by compensating for those applications that bypass the Windows API for timing by directly using the RDTSC (Read Time Stamp Counter) instruction. Applications that rely on RDTSC do not benefit from the logic in the operating system to properly account for the affect of power management mechanisms on the rate at which a processor core's Time Stamp Counter (TSC) is incremented. The AMD Dual-Core Optimizer helps to correct the resulting video performance effects or other incorrect timing effects that these applications may experience on dual-core processor systems, by periodically adjusting the core time-stamp-counters, so that they are synchronized.
This driver is for Windows XP only.
I think I remember having to install this driver to make things work with allegro
in my very old Windows Xp computer ( rests in pieces 
)
But will this also be a problem when using linux ? and is this still a problem ?
I don't know what you're talking about. I've got a dual core AMD on my WinXP machine, and allegro has always worked just fine. :/
Never had to 'patch' anything to get it to work.
Never tried it with Linux though, so who knows.
Your quoted section says that applies only to Windows XP... so Linux should be fine. And I've never heard anyone list that problem. I've been using AMD cpus for over a decade.
@ Chris KatKo that could be the case, but before making the switch I wanted to know if I could run into this problem.
( since there is no patch for Linux, but maybe because it is not needed in the first place)