I don't think there's anything fundamentally wrong with the POWER architecture. Just look at IBM today selling POWER8 and POWER9 systems. For example IBM Watso

I don't think there's anything fundamentally wrong with the POWER architecture. Just look at IBM today selling POWER8 and POWER9 systems. For example IBM Watson, which was featured of Jeopardy, was built on a POWER system. If you look at performance per watt, I don't think the G5 is that far behind the NetBurst architecture Intel was pursuing at the time. Pentium 4 Mobile laptops were absolute beasts to handle the power and cooling needs of the chip. Pentium M laptops used a completely different CPU design which evolved from the Pentium 3 and later became the basis of the Core/Core 2 series of chips. The main issue for Apple was that IBM couldn't make a processor that could work in a laptop (both for power and cooling reasons), and Motorola/Freescale were seriously behind schedule in shipping a dual core G4. Freescale eventually shipped their dual core in 2007. [1] So the main reason for Apple's switch was an immediate availability of mobile CPUs (which greatly outperformed the single core G4). The first Apple Intel products actually used the Core Duo, which was actually a laptop part. [1] https://en.wikipedia.org/wiki/PowerPC_e600 https://en.wikipedia.org/wiki/PowerPC_e600