CPU upgrades for computers have been around for decades, and DayStar was a prolific maker of them for Macs. The company advertised that its PowerCache cards could make a Mac IIci from 1989 even faster than Apple's high-performance IIfx...but were those claims actually true?
Sources:
PowerCache performance explanation: https://wiki.preterhuman.net/index.php?title=DayStar_PowerCache&mobileaction=toggle_view_desktop
"PowerCache IIci Beats Mac IIfx, MacUser, February 1991.
"PowerCache IIci," MacUser, December 1991.
"The Accelerated Course," Macworld, July 1991.
Macintosh IIfx photos (also a pretty cool site in general!): https://oldcrap.org/2019/07/31/apple-macintosh-iifx/
"Macintosh Quadras: Power but no pizzazz," Macworld, December 1991.
"Dual Dynamos: The Macintosh Quadra 700 and 900," MacUser, December 1991.
DayStar 68040 card photo: https://wiki.preterhuman.net/File:Turbo040-4.jpg
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