Hi, Tony,
It is possible to change the MAC address on some old motherboards with integrated NICs, if there's a special tool for (re)writing the bytes needed in the NVRAM or in the BIOS.

Recently I've done the exactly same thing for two socket A boards - ECS 748A and Asrock K7Upgrade600. The tools for the MAC recovery/change are brand specific, so probably you will be able to find the one for Asus boards too. I'm not sure if Asrock MAC restore/change DOS tool will work on Asus boards, but I can share it, if you can't find the one from Asus and you want to give it a try.

Good luck!

Thanks.
It'd be nice to know where the MAC is being stored. I somehow doubt it's in the BIOS as I can flash a BIOS from TRW on an empty chip and the MAC (I suppose) is retained? On more modern boards I usually see a small memory chip nearby the NIC chip which I suspect is the MAC address storage.
Looking at a pic of the board, I see a small 8-legs chip near the NIC chip. I'll have a look of what that is but I have a feeling it might be that. Worst case scenario I can remove it and re-program it myself. But if it can be programmed via software, why not.

If you don't mind sharing your tool, I can give it a go and see if by any chance it works. Thank you!

On my Asrock K7Upgrade600 board the MAC address was lost after a regular BIOS update procedure from the DOS command prompt. I didn't even knew, that there will be such a problem, but managed to restore the original MAC address by using the right DOS tool for this Asrock board model (the original MAC address is printed on sticker stuck to the board). So, I think in this case it was stored somewhere in the BIOS.

The case with the ECS board was totally different. I updated the BIOS with some "compatible" one for a DFI board from the DOS prompt, but it was not 100% success as the BIOS didn't like the chip it was stored in and refused to write its configuration on boot. And also it was impossible to restore the original BIOS with the DOS flashing tool anymore 😁 So I desoldered the BIOS chip from the board, then soldered a socket for it, reprogrammed the chip with the ECS BIOS by using EEPROM programmer and thought it was lost the MAC address during all these BIOS "updates" (like with the Asrock board). For my surprise the original MAC was still intact, so probably it is stored somwhere in NVRAM, but anyway I was already prepared with the suitable ECS/PCChips MAC restore tool just in case.

I just uploaded the archive with four versions of Asrock MAC address restore/change DOS tool here: https://limewire.com/d/hGnV3#PwsduQe3PK . I can't attach it in the post or message as it's 21+MB in size, sorry for this inconvenience. I don't remember from where I've downloaded this archive before, but for my Asrock board "MACU2.EXE" did the job.

Just use "MAC /?", "MACU /?", etc. in DOS to see how to use the command line switches.

Thanks, appreciated!

If Asrock compatible MAC restore tools don't work for your Asus board, just make a search on archived Asus support URLs (webarchive, you know) and possibly you'll find archived working link to download the tight tool for your Asus board model. I found the MAC tool changer for my ECS board this way.

BTW, I'm a fan of your youtube content and I like your videos with PC components repairs the most 😉

Good luck with your Asus board restoration!

ah thank you for your kind words - I am famous!

I had a look at the Realtek chip datasheet and there is an EEPROM. Surprisingly, the MAC address is not mentioned a lot in the datasheet but it would make sense it's stored there. The EEPROM has a checksum though so it won't be as easy as changing it with a programmer.

Thanks for the files - I am not so sure all manufacturers would have a tool to change their MAC address but I can try. I see the one you found has many folders for many NIC manufacturers but not Realtek I can see unfortunately. I'll try that anyway, you never know.

Well, in your case the MAC address can be stored in the EEPROM chip you're suspecting. There are different manufacturers of NIC controller chips, motherboards, motherboard models, BIOSes... so, different variants for MAC address storage place are possible.

Still the easiest way to change/restore the MAC address for an integrated NIC on a motherboard is by using some dedicated software tool (as in my two cases I briefly described), regardless of where the physically the MAC address bytes are stored.

If Asrock and even the so much hated ECS/PCChips have their own software tools for this job, I'm pretty sure, that Asus has too, as it was more respectful brand back in the days (even though I personally always prefered Asrock motherboards over the Asus ones). Just a matter of deep old web archives search and a pinch of luck 😉

P.S. Should I expect a video with your Asus "patient"?

aVd wrote on Yesterday, 20:08:

[...]

If Asrock and even the so much hated ECS/PCChips have their own software tools for this job, I'm pretty sure, that Asus has too, as it was more respectful brand back in the days (even though I personally always prefered Asrock motherboards over the Asus ones). Just a matter of deep old web archives search and a pinch of luck 😉

Being 'respectable' might actually make it less likely to have such a too - MAC addresses are supposed to be unique and unchanging so some vendors could be very cagey about options to do the exact opposite (even if it's relatively trivial to do it in software).

I've done a little digging and despite there being custom tools for other Realtek NICs (PCIe 8168 and some WiFi stuff), I can't find any for any old PCI NICs like this. But you probably don't need a custom tool, this is something that should be possible in a default Linux install using ethtool: https://blog.kanbach.org/post/how-to-permanen … -using-ethtool/

Out of interest: why do you want to change the MAC?

On modern modern boards its all stored in main bios chip together with serial numbers. Saves manufacturers $cents on parts and pcb realestate.
On something esoteric like Sun SPARCstations it was stored in NVRAM on RTC chip 😀
On Asus P5P800-VM it is U9 right above Realtek network chip. Original Asus BOM file:

105G020010602         燒 P  PCS       1.0000 06/05/19               2  N  N
2     EEPROM AT93C46-10SU-2.7 SOIC-8                      
3     ATMEL                  <G>                           U9,                 
4     MARKING:ATMEL XXX 93C46 SU27X
5     QVL:艾特梅爾,艾特梅爾,
6     客戶料號:                    品名規格:                                           
7    (05G020100630        )                1.0000 06/02/21                    N
8     EEPROM M93C46-WMN6TP   SO8                          
9     ST                         <G> 
10     MARKING:93C46WP
11     QVL:意法,
12     客戶料號:                    品名規格:                                           
13    (05G020100303        )                1.0000 06/02/21               S    N

Yes I have boardview https://drive.google.com/file/d/1om_Y1KsuuOA- … ew?usp=drivesdk

MAC address is software controlled in every NIC chip. OSes usually allow configuring your own, in XP its under Advanced/Network Address
win9x HKLM\SYSTEM\CurrentControlSet\Control\Class\{something?}\something\NetworkAddress

dionb wrote on Yesterday, 20:33:

Being 'respectable' might actually make it less likely to have such a too - MAC addresses are supposed to be unique and unchanging so some vendors could be very cagey about options to do the exact opposite (even if it's relatively trivial to do it in software).

I've done a little digging and despite there being custom tools for other Realtek NICs (PCIe 8168 and some WiFi stuff), I can't find any for any old PCI NICs like this. But you probably don't need a custom tool, this is something that should be possible in a default Linux install using ethtool: https://blog.kanbach.org/post/how-to-permanen … -using-ethtool/

Out of interest: why do you want to change the MAC?

Hi, @dionb,
On a second thought, there's a reason in your words about the Asus and the other "big" motherboard brands and how could possibly they've been supported their products back in the days.

Right now I'm too lazy to do a (re)search, if Asus once provided such a MAC restore/change tool for their motherboards, and I don't need such Asus tool for me. Tony is the one in need for it and I just tried to give him some directions, based on my past experience with erased MAC addresses due to BIOS updates.

As for the reason why we might want to change the MAC address on some old motherboard... I didn't changed any MAC addresses, I just restored the lost/erased bytes for the original ones (they are usually printed on a sticker stuck on some of the board's port) 😀 Still I may find some usecases as a reason for changing the MAC address from the pure technical point of view. For example - a damaged beyond repair hardware, which is replaced with new one.

Thanks for the Linux trick, I didn't knew about it.

On one hand MAC was treated s this magical static serial number, with big companies like Synopsys or Altera (mac + HDD Volume ID) using it to lock expensive software packages to individual computers. On the other every OS allows you to configure custom one 😀

dionb wrote on Yesterday, 20:33:

Out of interest: why do you want to change the MAC?

So I have a device where I'd like to enable a feature but the license for that feature is tied to the MAC address. The company, the devices, the IP (Intellectual Properties) have all long gone/expired so there is no way to enable that feature today. I have another device where the feature I want is enabled so one trick would be to change the MAC address of the device and upload the licence of the other one 😀
Again, it's all very vintage and very forgotten so nobody is going to be upset about that.

You're right though, I'll take a look with linux ethtools and see if by any chance there's something useful there.

Failing that I could remove the "good" eeprom, make a copy and re-use it where I want. It's a small chip, not a big deal.

https://huge-man-linux.net/man8/rtl8139-diag.html

-H and happy days? 😀

I've also found this for a similar NIC
https://www.youtube.com/watch?v=acxJMt6nT2g

certainly looks like it http://ilab.usc.edu/beo/rtl8139-diag.c and there doesnt appear to be any checksumming involved. set_hwaddr just writes 3 words at offset 0eh-13h and thats it.

oh cool. Thanks. I can try tomorrow.

If you can read whatever storage devices in your board, there's a good change you can figure out where the MAC address is stored.

There are lot of ways to find out what you MAC address is:
- Some BIOS can show it
- Some OS can show it
- A DOS packet driver shows it when it loads.
- Use a network "sniffer" to monitor packet traffic coming from that machine, the MAC address it containd in every packet sent.

You could then scan the content of EPROMs, Flash, EEPROMs, NVRAMs etc. and see if you can find it. Changing it however might be more difficult. These devices may have a CRC/Checksum to validate that they have not been corrupted, and you would have to figure out to calculatre and update that as well.

The question becomes "why?" - MAC addresses are unique to the local network (and in fact mostly unique worldwide), are not "routeable" and serve only to uniquely ID the system on the local network.

If you can change it, you would want to make sure it doesn't conflict with any other on your network. I do get that given the "globally unique" nature of MACs back in the day, some vendors also used them as a unique serial number - and if features are enabled/disabled based on MAC, you might want to change it. But just copying a mac from a similar system on your network would cause conflicts.

There is a MAC address range reserved for "local use", which is: AC:DE:48:xx:xx:xx but you would be unlikely to find any such MAC which enables locked-out features.

Fortunately vendors tended to do such things based on "range" and just tweaking the low byte of the MAC will make if different to the network, but possibly still in the right "enable range" for your vendor.

It's a little bit bizarre that companies back in the day considered a MAC address static enough to tie a software licence to it, yet nowadays current platforms like android etc. randomise the wifi mac at regular intervals for privacy purposes.