So, I recently purchased a computer scrap lot that turned out to be almost entirely junk. A decent amount of scrap value, for sure, but most of the parts I wanted to save from the lot were either damaged or had been stripped of their capacitors.

There were a few parts that looked okay though. One of them was a very generic looking Slot 1 + S370 micro-ATX board that had that classic PCChips look with the made up name printed on the northbridge heatsink. This particular board is a marked as an "Xcel2000" and has an SIS620 chipset, integrated SIS video, CMI8738 PCI audio and one shared ISA\PCI slot... not so good. It came with a 366Mhz Celeron Mendocino. Thankfully, it booted up fine. The BIOS setup showed the CPU set at 66x3.5=233Mhz, but I figured it was just because the CPU was locked and these settings were innactive. I ran some tests and it seemed stable, with the CPU reporting and performing correctly for a Celeron 366.

Since it was all working I decided to throw in some PCI VGA cards I'd harvested from the lot to test them out. First up was a CL GD5434, which worked fine. Then I tried out an AOPEN SIS 6326... and things got weird. It loaded a nice VGA BIOS screen and then started to display the startup messages... the screen had some alignment issues on my LCD so it was moving around a lot, but then I noticed that it now said "Celeron 550Mhz"... whuhhh?

I let it continue to boot from my DOS tester SD card, loaded Speedsys, and sure enough, the system was now running with a 100Mhz FSB, so the CPU was now at 550Mhz, up from 366! The speedsys benchmark confirmed that it was definitely really running at this speed. It also showed that the 8MB memory normally reserved for the integrated video was now freed up for system RAM (it seems to do this with any PCI video card installed). The BIOS setup still showed the same completely-incorrect 66x3.5 settings.

What on earth would cause this??? If I put the CL card back in or use the integrated video, it runs at 366, but with the SIS 6326 in the lone PCI slot, it overclocks the system by almost 60%!

I only own a few PCChips boards right now, but of the three, I have one with fake hollow-plastic cache chips, one that comes with a Duron overclocked via a 105Mhz FSB and now this one that overclocks the CPU when an SIS video card is installed.

I can't believe these boards even work. 🤣