Hi all,

I've a Mac Quadra 610 DOS compatible, running a "Houdini II" card, that packs an Intel 486DX2-66 and SB16 onboard. With this configutation I can install Windows 98 without issue.

I've a Kingston TurboChip TC5x86-133 CPU upgrade which POSTs on the above board without issue, DOS games run very well with no concerns - but booting Windows results in a "Windows Protection Error". This happens for both Windows 95 and 98 installs. Pull the CPU, put back in the 486-66 and it's fine. The 5x86 CPU is also detected using DOS hardware information utlities at the right speed.

For the Kingston upgrade, there are no DIP switches on the CPU upgrade, nor utility disc I can find to fiddle with settings (like write back/write through cache). The Apple BIOS for the card is not adjustable. I recall using the same 5x86 in a Quadra 630 DOS Compatible 15 years ago the same "Windows Protection Error" came up there too.

Where should I start to make this CPU compatible, thanks in advance.

JB