Note: some consoles may vary but I have done this method on about 5 or 6 consoles with Rev D and all boot within 40 seconds. 1-2 Closed J-P Open CAP Closed Phat setting CPU_RST - 14 centimetres https://www.youtube.com/watch?v=wU6P5rLNtjE
Best result with the Corona motherboards as they have built in Oscillator Crystal and have pretty stable boot times.