Henry S. Courbis of ReactiveMicro.com sent me an e-mail about a new Transwarp GS upgrade service he’s about to roll out. Apparently, he has worked out all the voodoo to reliably upgrade most stock TWGS boards from 6.25Mhz/7MHz to a stable 18MHz, or even 18.75MHz (some make it, some don’t). The upgrade requires a processor and oscillator replacement, a few new IC chips and an updated GAL set. In addition, you absolutely MUST keep your accelerator actively cooled or your smokin’ fast TWGS may end up smoking for other reasons.
ReactiveMicro already offers a similar upgrade service for Zip GS owners.
Update: a few pics of the TWGS upgrade conversion process (posted 03/16/08) are available here.
This is my opinion, but if you’re planning to run any GS accelerator faster than 10MHz or 12MHz, I strongly recommend that you add an internal booster fan. By itself, a stock Kensington System Saver probably isn’t going to circulate enough air through the Apple IIGS (the KSS needs a faster fan with quiet, high-performance bearings), and the MDIdeas/Applied Engineering Conserver with it’s awkwardly placed fan is certainly not up to the task either. Since the GS case was designed to cool by convection, you need to mount the booster fan so that it is oriented in the correct direction; to pull air from the card expansion area, into the power supply, and then up through the KSS exhaust. Mounting the fan in the wrong direction breaks the convection process, and will work against the KSS. Fortunately, most fans have an arrow on them indicating the direction of air flow so it’s a goof-free enhancement.
You may also consider replacing the stock power supply in your Apple IIGS with a smaller, more efficient Mini-ATX supply and LittlePower adapter. Your GS will run cooler from improved air circulation and the removal of that old, clunky power supply as a heat source. Yes, that was a [blatant plug] endorsement… but the LittlePower is a product I really like and I feel confident in recommending it.