Non plus cpus are pretty much already at their max. So usually even small overclock is not possible. Even some plus versions have trouble working at 600Mhz.

The K6-2 550 is indeed already at the max. Perhaps you could dive into optimising BIOS settings and improve RAM latency settings. The difference between poor and optimal RAM settings might be, in some cases, bigger than 50MHz extra CPU clock 😀.

Are you all smoking something? Have you actually ever tried overclocking a regular K6-2 on a good board?

Back in the day, when I had a K6-2 550 on an ASUS P5a as my main \ only machine, I had it over clocked to 660Mhz (120*5.5) on air.

Saying the 550 and even lower regular K6-2 CPUs are at their max is silly.

CXT CPUs commonly have another 50mhz in at least, the sticking point for pre-CXT was around 366-400, so if you had a pre-CXT 350, you may have been "at max" practically. There were meant to be some highly cherry picked 400s, but few and far between, very small yield.

So anyway, check 2x works on a lower FSB, check RAM/Cache timings backed off, check revision oddities of chipset (Early ALI Super 7 had some sticking point I think) Check you are getting voltage at CPU you're supposed to, if it's only getting 2.1 V or something it will hold it back. Also you might be getting volt droop at a higher clock, so maybe giving it 2.5 will help.

I ran a 500AFX at 570MHz for years, I think at 2.4v. I've seen 550AGR at 600MHz, at 2.5v iirc. I think some of the 533AFX will hit 600MHz. You can try and see what you get. Watch the temperatures on the CPU and VRM components.

If you search on this forum, there are probably lots of posts about overclocking the various K6 chips. If 600 is your goal, the "plus" chips are probably the easiest route. Good luck!

The K6-2 533 I had was possibly the worst overclocking CPU I've ever had. IIRC it was the 2.4 volt model and I had to boost the voltage to get 550 MHz out of it. The lower the core voltage the CPU is rated for, the better your luck will generally be for overclocking it.