A bit of info you might find quite interesting...
I was involved in the initial introduction of the PS/2 model 30 in late 1986. Code name was Palace. Considering you are in Australia, it most likely originated from our IBM plant in Wangaratta. It was the first of the PS/2 models, followed shortly by the model 50 and the model 80. That machine cost a fortune in its day, but it was well designed. I seem to recall there were two BIOS chips... I think they were odd/even addresses. I used to have the entire source code listing to the BIOS and Advanced Diagnostics on my PC at work, which I used to hack to make tests from. It would not surprise me your machine still functions. Prime spec parts were used throughout and the SMPS's were extremely robust. You will find the RAM is ECC.
The amount of testing per machine leaves what is done today for dead. You motherboard underwent a 12 hour dynamic burn-in test from about 5 deg C to 65 deg C, then it was functionally tested on a FACT tester imported from Boca Raton in Florida. (I now own that FACT test machine. The machine originally cost $350,000. I bought it for $100 and stripped it down make a nice ESD bench with built in power supplies.) As an assembled PC, your machine underwent further extensive testing. Less than 1% valid warranty claims were received.
The Palace motherboard was most likely the first surface mount PCB to be made in Australia, because we installed Australia's first SMT plant initially for the PS/2 family. If it were made in Wang, I could tell you the names of assembly and test people who put your machine together, and the names of the engineers involved. When the Palace was made, the Wangaratta plant had only about 90 full time personnel... a great place to work where we were like one big family. At its peak 10 years later there were the equivalent of 600 full time hires and we had the biggest electronics plant in the country by far. We made a few MILLION PCs there for all of Australasia and some of EU and the USA. The reason I moved to Wangaratta for the great opportunity to be at the forefront of technology and get to travel around the world. We had a ball, and in those days money was no object in getting things done. But in 1998, IBM cashed in by selling us off to a shonky startup which ceased business about 2 years later, leaving in its wake a path of social, electronic and economic desolation in Wangaratta.
A little known fact is that we also manufactured a very large volume of Apple Power MAC processors. My job was developing the hardware and software for the testing them. Because of the Power MAC and the IBM RISC systems, in 1995 we were the biggest exporter of non-primary produce in Australia.
Times have certainly changed. It is all gone. Except maybe for your machine, my FACT tester desk, and a plethora of HP and Tektronix test equipment scattered about Australia.