No problem at all if u got the latest BIOS. K6-III+ is just the mobile version with lower voltage like k6-2+ series.

Only bios update I have seen online seems to be for REV 5.2 instead of REV 3.0.

I had thought revision 4.1 and later were the only ones that worked and they had native support.

Definitely get the latest BIOS -- my AOpen X59 Pro would not support the + models until I flashed to the latest version.

Aren't there other differences between K6 III and III+? I thought I remember something about the K6 III being more compatible with legacy motherboards.

Can you even use bios that is meant for rev 5.2 in rev 3.0?

Anonymous Coward wrote:

Aren't there other differences between K6 III and III+? I thought I remember something about the K6 III being more compatible with legacy motherboards.

DO NOT EVEN TRY THAT...literally

Anonymous Coward wrote:

Aren't there other differences between K6 III and III+? I thought I remember something about the K6 III being more compatible with legacy motherboards.

Because K6-III+ is the mobile vision with a relatively low core voltage that some motherboards may not support. Technically, they are the same things in the same socket.

I'm about to put a K6-IIIE+ 1.6v CPU in a motherboard and run it at 2.1v (Going for 600+ Mhz Overclock)

Wonder if it will work

I think there are some initialization differences, but I don't know the specifics.
BIOS updates were required for the "+" CPUs, so it's not just a difference in Vcore. Some boards had officially supported BIOS updates, and others had some hacked ones created by users.

If using a BIOS that doesn't support the "+", I don't know if it will POST. It it does, then maybe there are DOS utilities that will take care of the extra steps.

When I got the motherboard it came with K6-II 350Mhz and I was hoping to buy K6-III+ from ebay if it supported it, but perhaps REV 3.0 is too old REV to have bios updateto support K6-III+ since I don't seem to find any other BIOS updates except the REV 5.2 one.

Lots of modified bios's here:
http://web.inter.nl.net/hcc/J.Steunebrink/k6plus.htm#patched

That link for the bios doesn't seem to be working.

Phil has that BIOS image on his site:
http://www.philscomputerlab.com/gigabyte-ga-5ax-rev-52.html

But isn't that just for the rev 5.2?

Your in uncharted territory already using a board before 4.1 with a K6 Plus chip. I haven't done a ton of research but everything I've read said thats the earliest version that works.
This site says the GA-5AX has native K6 Plus support - meaning you can use a regular manufacturer bios and it will work with the chip - http://web.inter.nl.net/hcc/J.Steunebrink/k6plus.htm

However this site says revision 4.1 is needed - http://compatlist.k6plus.com/

It looks like the bios on the first link is just the standard F4 bios from Gigabyte? You can get it here - http://www.elhvb.com/mobokive/Archive/Gigabyt … -5ax/index.html

Unless they changed some of the ICs on the board between versions, I would expect BIOS versions to be compatible across different board revisions. Between rev 4.1 and 5.2, for example, there was a position swap between the ATX and floppy connectors, but a cursory examination doesn't reveal any changes in the core logic or support chips.

Here's an article about a guy trying to turn a rev 3.0 board into a 5.1 by unsoldering a hard link and installing a jumper header. I haven't read further to see how it turns out, but board revisions are sometimes very simple like that.
http://www.madshrimps.be/vbulletin/f10/gigaby … -victory-44180/

To expand on my experience trying to run a + chip on the AOpen X59 before updating the BIOS...

-It did POST.

-It was recognized as "Unknown CPU-S @ <whatever I clocked it to>.

-Keyboard PS/2 input was spotty -- I'd have to restart multiple times for it to recognize the DEL press to get into BIOS.

-IDE devices weren't recognized properly, making it impossible to install an OS.

The things I notice that are different in my rev 3.0 compared to rev 5.2 pictures online. There is one more ISA slot and one less pci slots on my motherboard. The tables writen on my motherboard are different so highest Mhz is 100Mhz, highest multiplier is 5.5 and lowest voltage is 2.0. Also My motherboard has "AUTO" voltage setting that is missing from rev 5.1