If I've read this, it was so long ago I've forgotten, so I won't rate it. In general I love Frank Herbert. (I'm BCing this because I discovered it's a duplicate, yes I have a book problem, Step 1: I admit that I can not control my book problem.)

The blurb:
'''
PROBLEM - to build a complete human consciousness ... out of computer hardware and desperation!

Soon after the start they went mad, the three powerful, disembodied human brains that should have guided them for the 200-year journey to Tau Ceti. Could they manufacture a replacement before emerging from the Solarc System into nothingness? Would the circuits reproduce the characteristics they needed, characteristics like conscience, love and guilt? Or would they end up with a zombie? a monster? a power-crazy fanatic? - or a genius? What they did build was fantastic, ungessable. Yet, looking back, it was always on the cards.
'''

RELEASE NOTES:

TBR on the train or during lunch breaks

Much better than its garish cover suggests. Good ending

Picked-up at a bookcrossing meeting.