There are no K6-III non-plus rated faster than 450 MHz, and those are not very overclockable.
K6-2 non-plus 550 are relatively common, but have lower performance than a K6-2+/K6-III+ at the same clock.
K6-III+ officially only go up to 500MHz, there is a K6-2+ 550 though.

The K6-III+ 400 ATZ has the advantage that it is easily available, see German ebay: http://www.ebay.de/itm/201225100398
This is an embedded/industrial version which was seemingly used in cash registers.

500mhz with non-plus is mostly the limit from my experience. The non-plus version is much more compatible with older motherboards and there are not that much performance difference between 500 and 550mhz on the K6-III.

Agreed on compatibility. Difference between 500 and 550: You are surely right, but the difference should be bigger than with a K6-2 at those clocks. It is certainly not necessary to use the higher clock, for more speed a PIII should be used.
The big advantage of a K6-III+ over a K6-III is probably lower power consumption, it will run much cooler.

k6-3+550 is usually 20~40% faster than k6-2-550, depending on which benchmark.
k6-2-550 is NOT much faster than k6-2-300. due to lack of integrated cache, its performance scales badly.
you can see my results here: my socket7 cpu benchmark results

and it seems very difficult, if possible, for non-plus k6-3-450afx to overclock to 500 stably. however, there is a mobile k6-3-450ack model that uses same 0.25nm process as the standard k6-3 yet consumps less power, and i wonder if it can achieve 500 at 2.2v, which would be the second fastest socket7 cpu within the 550mhz wall.

Not willing to remove the heatspreader, there's a high chance it will kill the chip. I'd love to see a stable K6-2+/3+ system with 120MHz or 133MHz FSB, so that we can see just how much faster it really is.

My dream would be an AT board with a K6-III+ at 600+ MHz, using a higher clocked FSB, 256MB RAM and a Voodoo 5. I'd love to build something like that one day, fit in a full copper socket A cooler and fan replacement for the Voodoo 5. It would be so kickass and maybe slightly faster than a Pentium 2 400.
I've found that a K6-3+ 550 (5.5x100MHz) is right in between the Pentium 2 350 and 400, depending on the situation it has to handle.

Anybody know any really good AT boards, besides the obvious choice (P5A-B 😀 )?

Im pretty sure I posted benchmarks with a K6-3+ @ 5*120 MHz a month or two ago 😉

The system was very stable with only 2.0V using my GA5-AX but if I used more than one memory stick the performance took a nose dive what ever BIOS settings I used.
With a single 256MB stick the system was really really fast for a socket 7 system. The OS I used was Windows 98SE.

yeah thats quite impressive, but i would prefer staying at the 100*5.5 safe line to avoid risking with my collections, and my mvp3 platform gives 5:00 at that speed.

F2bnp wrote:

Not willing to remove the heatspreader, there's a high chance it will kill the chip. I'd love to see a stable K6-2+/3+ system wi […]
Show full quote

Not willing to remove the heatspreader, there's a high chance it will kill the chip. I'd love to see a stable K6-2+/3+ system with 120MHz or 133MHz FSB, so that we can see just how much faster it really is.

My dream would be an AT board with a K6-III+ at 600+ MHz, using a higher clocked FSB, 256MB RAM and a Voodoo 5. I'd love to build something like that one day, fit in a full copper socket A cooler and fan replacement for the Voodoo 5. It would be so kickass and maybe slightly faster than a Pentium 2 400.
I've found that a K6-3+ 550 (5.5x100MHz) is right in between the Pentium 2 350 and 400, depending on the situation it has to handle.

Anybody know any really good AT boards, besides the obvious choice (P5A-B 😀 )?

ali5 is obviously the only choice if you want to go for high fsb, and my vote absolutely goes to gigabyte 5ax, 5aa may do too for at form.
using voodoo2 or 3 would be more helpful for the k6-3 to catch up with pentium2, as their glide drivers are more optimized for k6s, and less dependent on intel's fpu. voodoo5 is too new and they have turned to focus on d3d before going bankruptcy.

F2bnp wrote:

Not willing to remove the heatspreader, there's a high chance it will kill the chip. I'd love to see a stable K6-2+/3+ system wi […]
Show full quote

Not willing to remove the heatspreader, there's a high chance it will kill the chip. I'd love to see a stable K6-2+/3+ system with 120MHz or 133MHz FSB, so that we can see just how much faster it really is.

My dream would be an AT board with a K6-III+ at 600+ MHz, using a higher clocked FSB, 256MB RAM and a Voodoo 5. I'd love to build something like that one day, fit in a full copper socket A cooler and fan replacement for the Voodoo 5. It would be so kickass and maybe slightly faster than a Pentium 2 400.
I've found that a K6-3+ 550 (5.5x100MHz) is right in between the Pentium 2 350 and 400, depending on the situation it has to handle.

Anybody know any really good AT boards, besides the obvious choice (P5A-B 😀 )?

I'm pretty sure P5A-B is the gold standard. Once you have one of those, why would you want anything else?

Skyscraper wrote:

Im pretty sure I posted benchmarks with a K6-3+ @ 5*120 MHz a month or two ago 😉
The system was very stable with only 2.0V using my GA5-AX but if I used more than one memory stick the performance took a nose dive what ever BIOS settings I used.
With a single 256MB stick the system was really really fast for a socket 7 system. The OS I used was Windows 98SE.

Impressive indeed! My K6-III+ @ 5.5x100MHz scored 8372 CPU Marks.
Would you mind doing some more testing with a Voodoo 3 and some games? I made a thread about a year ago, could perhaps test some games by getting as close to this as possible? I'd really love to see how much of a difference FSB does, if 3DMark 99 is a solid indication, we may be in for a real treat.

Unfortunately, I can't get any higher with my GA-5AX board, it may have to do with the fact that it is rev4.1, but I think I can maybe push 110MHz. 115 and upwards is off the question I'm afraid!

Sliderider, I'm not saying I own an ASUS P5A-B, I'd love to own one! Just asking what other alternatives are around.

F2bnp wrote:

Impressive indeed! My K6-III+ @ 5.5x100MHz scored 8372 CPU Marks. Would you mind doing some more testing with a Voodoo 3 and som […]
Show full quote

Impressive indeed! My K6-III+ @ 5.5x100MHz scored 8372 CPU Marks.
Would you mind doing some more testing with a Voodoo 3 and some games? I made a thread about a year ago, could perhaps test some games by getting as close to this as possible? I'd really love to see how much of a difference FSB does, if 3DMark 99 is a solid indication, we may be in for a real treat.

Unfortunately, I can't get any higher with my GA-5AX board, it may have to do with the fact that it is rev4.1, but I think I can maybe push 110MHz. 115 and upwards is off the question I'm afraid!

Sliderider, I'm not saying I own an ASUS P5A-B, I'd love to own one! Just asking what other alternatives are around.

I do not have space at the moment 😀
But until I find some space and time here is a screenshot of the system running GL-Quake (32bit) using a Geforce 3.

And a screenshot of the system running Quake III (32bit) using a Geforce 3

I did some sandra tests on my K6-3+ running at 133x4.5 on a P5A-B. The ram timings are 2-2-2. It's done on XP SP3 and sandra 2005SR2, which might have different assessment standards.

I still can't stabilize it enough to run superpi, though 🙁

My K6-II 450, 500 & K6-III 450 don't overclock well. K6-II 450 won't do 500 and K6-III does 500 and that's it. I haven't tried to OC K6-II 500 yet, but actually don't expect much 😒

But when I get some time, I'll try to compare OC'ing with Asus P5A-B, Gigabyte GA-5AX and AOpen AX95PRO.

@kixs, The older chips don't really clock well. You might get a little lucky with the K6-2, but the K6-III is not going to get you far. The K6 Plus CPUs are the ones that clock a bit better. It is almost guaranteed that by buying a K6-2/III+ 400 you're getting yourself a chip that can almost always do 550MHz and usually 600MHz.

I actually had some interesting developments. I'm now running the system at 605MHz (5.5x110MHz) at 2.6V. I'm using a small Socket 7 cooler that I found on a K5 system and it is getting hot down there! Will probably replace it with something else ASAP.
System seems stable so far, got Quake doing timedemos just fine, 3DMark99 Max finished 2-3 times and I even tried the Outcast demo to check stability. Next up, I'm planning to try Quake 2 3DNow! and Quake 3.

I don't think I'll be able to get anywhere higher with this board, I'll need the 5.2 revision as that one has a different divider for the AGP bus.

F2bnp wrote:

@kixs, The older chips don't really clock well. You might get a little lucky with the K6-2, but the K6-III is not going to get y […]
Show full quote

@kixs, The older chips don't really clock well. You might get a little lucky with the K6-2, but the K6-III is not going to get you far. The K6 Plus CPUs are the ones that clock a bit better. It is almost guaranteed that by buying a K6-2/III+ 400 you're getting yourself a chip that can almost always do 550MHz and usually 600MHz.

I actually had some interesting developments. I'm now running the system at 605MHz (5.5x110MHz) at 2.6V. I'm using a small Socket 7 cooler that I found on a K5 system and it is getting hot down there! Will probably replace it with something else ASAP.
System seems stable so far, got Quake doing timedemos just fine, 3DMark99 Max finished 2-3 times and I even tried the Outcast demo to check stability. Next up, I'm planning to try Quake 2 3DNow! and Quake 3.

I don't think I'll be able to get anywhere higher with this board, I'll need the 5.2 revision as that one has a different divider for the AGP bus.

2.6V wow 😲
I had the feeling that one might have to raise the voltage when using a small aluminum cooler, which will worsen the heating problem. When using big bulky copper cooler you can actually lower the voltage.
What's the clock generator on rev 5.2? Does it provide 1/2 divider for AGP and 1/4 for PCI?

Hey fellas, didn't want to start a new thread about this so I'm bumping this one.

I've been meaning to implement my crazy idea from before for some months now. Basically, I'd love to build an AT system with a K6-3+ at 600MHz and higher than 100MHz FSB, ideally 133MHz. Adding a Voodoo 5 in there would also be pretty frickin' sweet.
Now, I've taken a better look at the situation and it seems I will have to go with either the P5A-B or GA-5AA from ASUS and Gigabyte respectively, if I want to attempt all this on an AT system. Unfortunately, I'm having a hard time deciding between the two, so let's get some quick questions going:

a) I know a lot of people have had great success clocking their K6+ CPUs at 600MHz with a 100MHz FSB, but has anybody here achieved stability with 120MHz or 133MHz FSB? I've been thinking about cooling the CPU with one of the copper Startech coolers and maybe installing a heatsink on the northbridge as well.

b) I found the AGP/PCI dividers for the P5A-B, but unfortunately I couldn't for the GA-5AA, could anyone provide me with these?

c) Am I going nuts? 🤣

I like the Asus boards better but when it comes to overclocking the gigabyte should go higer. I think the Asus boards are good up to 115-120mhz (stable).

Hi,
From my experience (I'm from k6plus forum), K6-2+ and III+ both achieve 600mhz at +0.1 vcore and was rock solid on Gigabyte GA-5AX rev. 5.2 / Epox MVP3G2/ MVP3G5.
I was able to do a little optimizations on the Epox ones with vpcredit to enhance memory performance.
The best combo should be 112mhz x 5.5, 6x multi always gives worst memory performance.
I used to play a lot with those cpus.
I remember smooth gameplay at 1024x768 with:
Age of Mythology (really demanding, had to set down graphics options)
Hitman
Max Payne
F22 Raptor (of course... Even on a p200@300mmx)
Civilization IV (still the best for me)
Wing Commander IV
Wind Commander V (aaawww)

And DOS games like Privateer II, Wing Commander III, USNavy fighters 97

Too bad the screens of my 3dMark2001 are gone from the thread...

http://www.k6plus.com/phpBB3/viewtopic.php?f=3&t=2001

You can find useful info on drivers combo and vpcredit optimizations for mvp3.

I'd just compare the info from GA-5AA and GA-5AX since they are quite similar except being AT and ATX. At least I wouldn't expect the GA-5AA to be better.
From the GA-5AX manual (5.2 revision):
The relevant table shows that the AGP divider is either 1/1 or 2/3 (ie. 87MHz AGP for 130MHz FSB). Is suppose PCI will stay AGP/2.
The manual also says:
"Note: We don’t recommend you to setup your system speed to 105 , 110 , 115 ,
120 , 125 , 130 , 135 or 140 MHz because these frequencies are not the
standard specifications for CPU, Chipset and most of the peripherals.
Whether your system can run under 105, 110, 115,120, 125, 130, 135 or
140 MHz properly will depend on your hardware configurations: CPU, SDRAM, Cards, etc."

Wasn't there a post here recently about some SS7 board (SiS IIRC) which had a proper divider for FSB133? Somehow I remember replying in that thread, but I can't find it.

Thanks for the info, I guess both boards are rather identical, I'll go for whichever then and hope for the best. I guess 120MHz FSB should be doable.

The post you're referring to is on the first page for this thread. Unfortunately, that board lacks AGP and is also micro-ATX, where as I'm really looking for a Baby AT board. What a shame 🙁.