Ibm pc 330-466dx2 Type 6571-l3b \ VOGONS

Ibm pc 330-466dx2 Type 6571-l3b

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First post, by Mowdy

Posted on 2019-07-20, 14:58

Mowdy Offline

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Posts: 16
Joined: 2017-09-13, 17:36

Hey peeps. is it really true that this machine cant use a 80486 66mhz cpu that max speed is 50mhz ?

This site says 66mhz
http://mastodonpc.tripod.com/personal/6571-l3b.html

But the schematic says 50mhz
http://ps-2.kev009.com/pcpartnerinfo/ctstips/a5a2.htm

When we put the 80486 66mhz cpu in it the pc its only running 50 MHz

Can someone help a bit here either if it is possible to get it to run at 66mhz or its not possible at all

Reply 1 of 3, by Deksor

Posted on 2019-07-20, 15:02

Deksor Online

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Joined: 2016-06-07, 14:37

The 486DX2 is the first x86 to incorporate a clock doubler as far as I know, so back then the "CPU speed" and "FSB" were often mentionned as the same thing because the CPU used to run at the FSB speed.

So if your motherboard is capable of running a 486DX 33, this means it's capable of 33MHz FSB, so you can run a DX2-66 and it will run at the correct speed.

Trying to identify old hardware ? Visit The retro web - Project's thread The Retro Web project - a stason.org/TH99 alternative

Reply 2 of 3, by Mowdy

Posted on 2019-07-20, 15:57

Mowdy Offline

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Joined: 2017-09-13, 17:36

It why is it only says 50 MHz when CPU is a 66mhz

Reply 3 of 3, by evasive

Posted on 2021-12-30, 14:08

evasive Offline

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Joined: 2020-04-28, 19:07
Location: Nederland

Because the CPU runs at 33MHz on the outside but 66MHz on the inside. It has a frequency doubler, hence the "X2" in the name.

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