This may be the one you already have, but have a look. https://web.archive.org/web/20051109005128/ht … ex.php?count=-1

I also have this board. My board is rev 1.A but I am using a bios for a rev 1.1 board (bios v2.1) with Bios patcher to enable K6-2 and K6-3 support as well as fix the UDMA bug and add large drive support

https://theretroweb.com/motherboards/s/msi-ms-5158-tx5

I tried the Wims bios already but I also had issues with it not detecting my 32Gb CF card correctly.

I can confirm that the patcher fixes the UDMA bug - my CF card is UDMA 5 - which is what the boot screen shows it as before the patch. Now it's patched, it correctly shows UDMA 2. DMA is enabled in windows 98 and I'm getting 30MB/s transfer speeds. I have not tried the computer with anything higher capacity than this as yet.

Does your motherboard have the hardware monitor chip - CPU temperature/fan speed? It is located to the left of the 3rd ISA slot (the one below the PCI/ISA shared slot) in the image of the board on theretroweb, it's not populated and I get the impression not many boards come with it, but if you have it, it may cause more issues if you use the 1.1 bios

This is according to Jan (aka Chkcpu) Credit to him for finding out this information

Hi brian105,

I’m presently working on a patched BIOS for the MS-5158 v1.(A)/v1.1 boards.

Indeed, I have been working together with FullYes to select the best BIOS to patch. FullYes tested a lot of different BIOS versions on its v1.A board, including an OEM version that came with his board. On my end, I did a detailed analysis of this OEM BIOS and the Ver 1.4 and 2.1 from TRW.

This is what I found:
The code base used for the 10/17/97 OEM BIOS is at least half a year older than that of the v1.4/v2.1 BIOSes on TRW. So the OEM BIOS looks more like a mid 1997 BIOS, while MSI’s versions 1.4/2.1 are clearly 1998 BIOSes.
I see this in the limited K6-2 support in the OEM BIOS, including the K6-2 bootloop issue as present in a lot of early 1997 Award BIOSes. The MSI BIOSes have better K6-2 support and have this bootloop issue fixed.

I also see more detailed ATA and ATAPI support in the MSI BIOSes, which could be beneficial for certain types of CD-ROM and CF or SD cards.

All of these OEM and MSI BIOSes, including the Wims BIOS, lack Write-Allocation support for the K6-2/III, so that’s why the rom.by patched BIOS versions, as tested by FullYes, show better performance. Of course my patched custom BIOS will add this WA support as well.
What the rom.by BIOS patcher doesn’t fix is the Auto Vcore control from the BIOS for K6-2+/III+ CPUs, via the hardware monitor chip. But if your board doesn’t have this chip, this is of no consequence.

Finally, a comparison between the MSI v1.4 and v2.1 BIOS revealed only one little difference. The CPU Fan and Chassis Fan items from the hardware monitor have been interchanged. Probably due to a minor trace change between MS-5158 rev 1.(A) and 1.1 boards.
Again, for boards without the hardware monitor circuit this is of no consequence, and you can use either v1.4 or v2.1 to upgrade your BIOS, as for all other functions, the v1.4 and v2.1 MSI BIOSes are byte for byte identical.
I have selected the MSI v2.1 BIOS to make a custom BIOS with all the fixes I know, so also boards with hardware monitor are supported. BTW, does your board has the hardware monitor? If so, you should see an extra SPECIAL FEATURES menu in the BIOS Setup.

I will report back when I have more,
Jan

Thanks Jan. I didn’t want to steal your thunder here

@brian105, I can send you the patched v2.1 bios if you want. Or wait for Jan’s superior version. But worth knowing first, if you have the hardware monitor chip or not.

Repo Man11 wrote on 2026-01-20, 00:24:

This may be the one you already have, but have a look. https://web.archive.org/web/20051109005128/ht … ex.php?count=-1

Yep, this is the one I tried.

FullYes wrote on 2026-01-20, 13:42:

Does your motherboard have the hardware monitor chip - CPU temperature/fan speed? It is located to the left of the 3rd ISA slot (the one below the PCI/ISA shared slot) in the image of the board on theretroweb, it's not populated and I get the impression not many boards come with it, but if you have it, it may cause more issues if you use the 1.1 bios

My board does not have the hardware monitor chip it seems, it looks identical to the image on theretroweb. Per Jan's description, I also don't see the "Special Features" section in the BIOS.

I can test patched BIOSes if required as well. Thank you for your help!

@brian105, @FullYes,

The patched MS-5158 BIOS is ready and I’ve send you both a copy via PM.
When you are able to test it, do let us know how it works.

This is the list of changes I’ve made to the latest V2.1 040898 BIOS:
- Added support for the K6-2+ and K6-III+ CPUs, including Write Allocation for all K6-2CXT/III, K6-2+/III+ CPUs
- Expanded the CPU Type display routine for correct display of the AMD K6(tm)-2, K6(tm)-III, K6(tm)-2+, and K6(tm)-III+ strings
- Added 6.0x83 (500MHz) and 6.0x75 (450MHz) support for the K6-2CXT, K6-III, K6-2+ and K6-III+
- Added support for the IDT WinChip 2(A)(B), the mobile Pentium-MMX (Tillamook), and the Cyrix MII when set to x4 multiplier mode
- Fixed the 32GB and both 64GB IDE HDD limit bugs for full 128GiB support. These are the ‘new community’ fixes that allow drives up to 640GiB to be attached, although the BIOS will then only 'see' the first 128GiB due to its LBA28 limit.
- Fixed the UDMA mode bug for correct Win98(SE) UDMA 2 support.

This MS-5158 patch J.2 BIOS should work on all board Revisions 1., 1.A, and 1.1, with or without the LM78 Hardware monitor chip. However, if you use this BIOS on a Rev 1. or Rev 1.A board with Hardware monitor, you may notice that the CPU Fan and Chassis Fan monitor function is interchanged.

Cheers, Jan

Thank you Jan!

I am now running your BIOS on my machine. Works perfectly!

I flashed the bios using uniflash. (I need to double check which version, but think I got it off TRW)

Hi brian105 and FullYes,

Thanks for testing the patched MS-5158 BIOS and reporting back, both here and via PM. 😀
This now concludes the beta testing of this patch J.2 BIOS version and here is a copy for the community.

At the next update, I will add this BIOS to my k6plus webpage as well.

Cheers, Jan