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First post, by majestyk

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Currently I´m testing an old FIC 486-PAK-3 mainboard that was used in AT&T´s Globalyst 520.
I updated it´s BIOS from 1.00 to 1.06 (from the NEC´s website).
It´s now equipped with 64 MB of EDO memory and a 486 DX2-66 CPU. This CPU is correctly detected and identified by the BIOS.
The proprietary L2 cache stick is not installed - due to it´s rarity...

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So I ran some initial tests like Speedsys and Sysinfo:

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I couldn´t believe my eyes when I noticed CPU benchmarks. That´s a joke for a DX2-66 right?

There aren´t too many BIOS options and they don´t affect CPU performance. On the board there are no jumpers, just a microswitch to select between 25 MHz and 33 MHz FSB.
What could be the issue here?

Reply 1 of 3, by megatron-uk

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Wow, that Norton result is slower than several of my 20MHz 286 boards. Even without level 2 cache fitted the scores should be way, way higher.

Obvious question though: is the turbo switch enabled? Does it use a keyboard combination to enable turbo rather than a physical switch perhaps?

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Reply 2 of 3, by majestyk

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I found a picture of the frontpanel on the net, there´s no hardware turbo switch, just "power" and "power management". The latter being some energy saving feature I suppose.
Edit: In BIOS there are several options under "Power Management", also for slowing down or halting the CPU, but those are all disabled and should not apply.

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I also tried "Ctrl + Alt + - / +" to no avail.

Reply 3 of 3, by majestyk

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O.k., this seems to be CPU dependant.

1.) Intel 486SX -> the system won´t boot from floppy, CPU detected correctly
2.) Intel 486 DX2-50, Intel 486 DX2-66, AMD Am486 DX2-66 all detected correctly and all are extremely slow at 14.5 points in Sysinfo.
3.) AMD Am 486 DX4-100 falsely detected al DX2-100, slow at 14.5 points.
4.) Intel 486 DX4-100, detected correctly, in Sysinfo it´s at 216 points!
5.) AMD Am5x86-133, detected as DX4-100, same benchmarks as 4.).

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I had to assemble a little self made VRM for the 3.xV CPUs to run.

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But what´s the reason for this behaviour? Seems like everything in the DX2 class is being slowed down to a kind of turbo mode.

The Globalyst 520 was available with 486 DX2-50, 486 DX2-66 or 486 DX4-100 CPU. So it´s not surprising the DX4 works properly. But why don´t DX2 models?

By the way, this home made VRM fits perfectly on the "FIC 486 GAC-2". 3 jumpers need to be removed, because this board does not have the MOSFET switch for automatic 5V CPU detection.

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Unlike the PAK-3 the GAC-2 detects ALL CPUs correctly no matter if Intel or AMD, DX, DX2, DX4 and all run at full speed. (There are 2 jumpers for SX models.)
I wish the 256K Cache Sticks could be built as easily as the VRMs.