GA-586ATV Rev 4B: AMD K6-2+ 450/ACZ restart loop

Don't ask how to over-clock.
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gmlb
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Joined: Thu Mar 16, 2017 10:11 pm

Hello.

I got a Socket 7 Motherboard which is a Gigabyte GA-586ATV Rev. 4B, a later revision which uses a Raytheon RC5041 regulator (https://pdf.dzsc.com/RC5/RC5041.pdf) and can supply the core voltage from 2.1v to 3.5v. Out of curiosity I decided to try the patched BIOS that includes support for K6-2, K6-III and K6plus, and for large HDD up to 128GB found at: http://web.inter.nl.net/hcc/J.Steunebrink/k6plus.htm

I used a Pentium CPU to be able to flash the BIOS successfully, then upgrade the CPU with an K6-2+ 450/ACZ running at 6 x 66 Mhz (using the x2 multiplier since it is interpreted as x6). The POST recognizes the CPU properly as a K6-2+ 400mhz and started the memory test, however after the memory test passed and before the floppy and IDE drives are being detected the computer starts rebooting with a black screen and the POST screen appeared once again to perform the memory test, once it has passed it reboots once again, rinse and repeat. I can't even enter the BIOS setup, since it also reboots the computer.

I have cleared the CMOS stored on the RTC battery and made sure that the Video and System BIOS Cacheable was disabled prior replacing the CPU, also I unplugged the floppy and IDE drives from the motherboard but to no avail. Only after switching back to the Pentium CPU, everything worked fine.

I wonder it it has to do anything with EDO RAM (using 2 x 32MB Nanya 60ns), the inability to set the voltage manually on the motherboard (there is a voltage-related DIP switch which forces 3.2v for the original AMD K6-233. Does the patched BIOS sets the voltage to 2.1v when using a K6plus?) or something else.

The support for large HDD worked fine though.
gmlb
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Posts: 6
Joined: Thu Mar 16, 2017 10:11 pm

I have decided to try again with the K6-2+ and replacing the EDO ram with 2 x 8MB to see if the restart loop has something to do with this and to my surprise I was able to past the POST memory count without issues. However, the good news ends here because when I restart by doing a soft reboot or Ctrl+Alt+Del the screen stays black and when I try to install more than 16MB of RAM, the reboot loop reappears.
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