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How to use MHz display on AT case?

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First post, by mrzmaster

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Hello,

For the past several years, I've been very slowly collecting parts for a build centered around an Asus P5A-B and Pentium 233MMX. I recently acquired one of the final parts for this machine, a NOS baby AT style case with a NOS AT power supply. The case has an LED display (as well as a turbo switch) on the front to show the clock speed of the CPU. I'm assuming the display gets fed by the turbo LED header connector, however, the P5A-B does not appear to support this.

Is there any way to get the case's LED display to show the CPU clock speed using this particular motherboard? Thanks!

Reply 1 of 2, by jakethompson1

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Believe it or not (I didn't know this in period-correct times and only realized later), they're completely for decoration. What MHz value is displayed is set by jumpers on the back of the LED screen. All it knows is whether turbo is on or off and shows whatever you've set; it can't actually read the MHz value off the motherboard or anything.

Reply 2 of 2, by wbahnassi

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Majority of Pentium motherboards don't support the turbo switch. Unless you're in for some electronics, the only thing you can do is config the case's turbo display to show "HI" which was very common at the time on Pentiums installed in AT cases. But the turbo switch button won't do anything in your... case (pun intended 😁).

If you must enable the turbo function, I think the Turbo Blaster project will work for your Pentium.

Turbo XT 12MHz, 8-bit VGA, Dual 360K drives
Intel 386 DX-33, Speedstar 24X, SB 1.5, 1x CD
Intel 486 DX2-66, CL5428 VLB, SBPro 2, 2x CD
Intel Pentium 90, Matrox Millenium 2, SB16, 4x CD
HP Z400, Xeon 3.46GHz, YMF-744, Voodoo3, RTX2080Ti

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