How to get a 1x multiplier on a K5 \ VOGONS

How to get a 1x multiplier on a K5

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First post, by TandySensation

Posted on 2015-04-11, 20:30

TandySensation Offline

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I've read a few threads that say a K5 has a 1x multiplier option but I couldn't find details on how to set it and if it's only available on a socket 5 board.

I have an AMD-SSA/5-75ABR but no motherboard for it. I do have a couple of SS7 boards, can I run it with a 1x and a 75mhz bus to get the right speed? I'm hoping I can set some multiplier and have the K5 reinterpret it as 1x.

Reply 1 of 5, by kithylin

Posted on 2015-04-11, 23:11

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There are some socket 7 motherboards that support 50 Mhz Bus Speed, most of them are intel-only though but I have seen some with the early VIA chipsets that will do AMD chips at 50 mhz if you look some.

FYI even at 1x multiplier, running that chip on any system with more than 50 Mhz Bus speed is technically overclocking it and may lead to serious instability in these chips.

Reply 2 of 5, by TandySensation

Posted on 2015-04-13, 18:28

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2.5x

Set the FSB to 60 and used a 1.5x initially to see if it would post. It booted up at 90 and even ran a few tests, all seemed stable at 3.4v

Tried a few different settings and nothing until 2.5x... then it happened... the monitor light went blue, felt like forever to post but I kept my fingers crossed.. and Booyaa! 60Mhz! I've never been so excited! Maybe I need to try some other hobbies.

Posted this in case someday someone else wants to know without doing the trial and error thing. My K5 is an older model, the newer gold topped ones might be different.

Reply 3 of 5, by PcBytes

Posted on 2015-04-13, 18:40

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TandySensation wrote:
2.5x […]
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2.5x

Set the FSB to 60 and used a 1.5x initially to see if it would post. It booted up at 90 and even ran a few tests, all seemed stable at 3.4v

Tried a few different settings and nothing until 2.5x... then it happened... the monitor light went blue, felt like forever to post but I kept my fingers crossed.. and Booyaa! 60Mhz! I've never been so excited! Maybe I need to try some other hobbies.

Posted this in case someday someone else wants to know without doing the trial and error thing. My K5 is an older model, the newer gold topped ones might be different.

Let me guess,your K5 is a ceramic topped one? (not gold)

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Reply 4 of 5, by TandySensation

Posted on 2015-04-13, 19:05

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Yes, it's ceramic. I believe the gold ones are the newer style. I read someplace that 2.5x is 1.75x multiplier for newer model of the K5. Might only be possible to get 1x with the older ones.

Reply 5 of 5, by alvaro84

Posted on 2024-08-16, 17:17

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Sorry for the necromancy but I did some sniffing around these K5 CPUs and found that the 1x/1.5x multiplier set is only available in the earliest model of the K5, the one that has the 0x500 CPUID. The later stepping that identifies as 0x501 apparently has a 1x/1.5x/2x set and the latest one (PR133/166/200) has the famous 1.5x/1.75x/2.0x. This revision is also faster.
It's worth noting that my 0x500 piece (PR90, early 1996) has very archaic looking markings on its fully ceramic casing.

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