Performance wise, yes they are faster, but anything that struggled on your K6-2 is not going to suddenly become silky smooth on the III+.

Once the BIOS supports the CPU, it should be smooth sailing, just don't expect any miracles with the performance, maybe 15 to 20% clock for clock?

According to feipoa's "ULTIMATE 686 BENCHMARK COMPARISON":

Overall performance:

• - K6-3+ 550 ; 317.1 points
  - K6-3+ 500 ; 291.6 points
  - K6-2 550 ; 284.4 points
  - K6-3+ 450 ; 266.2 points
  - K6-2 500 ; 263.6 points
  - K6-2 450 ; 242.2 points
  - K6-3+ 400 ; 239.8 points
  - K6-2 400 ; 222.1 points

@400MHz, 100MHz FSB:
K6-3+ is 7.97% faster than K6-2.

@450MHz, 100MHz FSB:
K6-3+ is 9.91% faster than K6-2.

@500MHz, 100MHz FSB:
K6-3+ is 10.62% faster than K6-2.

@550MHz, 100MHz FSB:
K6-3+ is 11.50% faster than K6-2.

Interesting, thank you for the replies.

My current K6-2 is a 475Mhz overclocked to 500Mhz. I am not sure it will do 550Mhz, though. I think K6-IIIs are available up to 450Mhz (the higher-clocked ones are very rare). Can a 450Mhz be typically overclocked to 500Mhz? 550Mhz?

Yes 550 should be easy.

The "best" chips are these 1.6V embedded CPUs. They do 550 on quite low voltage.

The benchmarks I did are all in games, you will see more around 15% or 20% or so improvement, which is nice, but nothing you will really notice. The other benefit of the III+ are:

- software selectable multiplier
- on-die cache with no size limitations (So you can use more memory without suffering a speed penalty)
- Lower power consumption

PhilsComputerLab wrote:

The "best" chips are these 1.6V embedded CPUs. They do 550 on quite low voltage.

Which ones would those be? The one above is a 450ATR, and there is also 450ACZ. Both say 2V on the chip.

They are the same, but 1.6 V. Years ago someone had hundreds of them on eBay, that's when I got a few for myself. Looks like they are harder to find, can't be too choosy then.

PhilsComputerLab wrote:

They are the same, but 1.6 V. Years ago someone had hundreds of them on eBay, that's when I got a few for myself. Looks like they are harder to find, can't be too choosy then.

I think I know which seller you're referring to. The seller was from Germany iirc?
All those ATZ 1.6v chips he send me were brand new and all of them worked (tested all of em).

@dr_st: It's important to keep in mind that the older desktop chips (K6-2 and K6-III) are basically different chips. The + ones (K6-2+ and K6-III+) were basically a die shrink and often didn't have default BIOS support. A few boards will actually not really work well with the die shrunk chips, but will with the older desktop versions (of which K6-III is the more interesting part...and also always seemed to be much less common).

And as has already been mentioned, there were a couple more changes related to software CPU multiplier management.

Hm. Just realized that a K6-2+ is also an option, as it is closer to a K6-III than to a K6-2 (essentially a K6-III+ with half the L2 cache). How do these perform / overclock?