Cga.8086 wrote:should i just find an K6-III+ and forget about the k6-2+
As PCBONEZ mentioned, first make sure your board has BIOS support available for the "+" CPUs. They weren't originally intended for desktop boards, so often this requires using a Beta BIOS or 3rd party hacked BIOS. There's a site somewhere that has a long list of which boards have "+" compatible BIOSes available.
But if it will work, then either of these are great CPUs. The K6-3+ is slightly faster but it's only a small difference. The K6-2+ is much more common on eBay and cheaper, so unless you really want to max out the board, the 2+ is fine.
Either will typically clock into the ~550MHz range easily. Above that you start having to flog it. A conservatively overclocked K6-2+ will outperform any original K6-3, and is barely any slower than the K6-3+ at the same clock.
You'll want the board to have Vcore settings of 2.0V or less. AMD's datasheets for these chips warn against anything in excess of the intended range over the long term (I'm not sure how much to take that seriously), but additionally they list 2.2V as the absolute maximum (and I do take that seriously). This means that even a jumper setting of 2.1V might be slightly risky due to imprecision and transients.
Your board might have undocumented voltage settings. Mine for example goes down to 1.3V, but the board manufacturer only listed the options they thought were relevant at the time of manufacture.
All K6 chips are unlocked, but only the "+" chips can change speeds on the fly.