Re: AMD K6 works at 90 MHz but fails at 166 MHz?

Donnie Savage (dsavage@cisco.com)
Mon, 02 Jun 1997 15:39:24 -0400


felix> Hi recently bought an AMD K6 to speed up my compile cycles. My
felix> old motherboard, an ASUS TP4XE didn't handle 166 MHz, the
felix> screen stayed black, no sync signal, no beep, nothing. But
felix> with 90 MHz, it worked, was quite a bit faster, yet I bought a
felix> 166 MHz processor so I want to run it at 166 MHz. So I tried

[snip]

felix> Does anyone have any suggestions? Clearly, I can't give the
felix> motherboard back as it works fine with Windoze 95.

I had a similar problem. NT worked and Win95 worked, Linux would not
work. Multiple email messages with BioStar (motherboard manufacture)
only resulting in frustration. Went out and bought a new mother board
and all is well!

I run the system 7/24 and it has ran flawlessly for weeks. Sound
and graphic programs works fine. Recompiled 2.0.27 and 2.0.30 with no
problems (full compile in 5 minutes)

But here are a few pointers:
1) make sure the BIOS supports the K6. If it does not then the
system is subject to lock ups

2) verify the core voltage is set properly. It should be
2.6Volts (though over clocking may require 2.9Volts)
higher/lower voltage settings will result in hangs/lockups.

3) Disable external cache and see if the lockup disappear. I
once have a P5-90 motherboard that ran fine with Win95, but
not linux. Turned out the cache chips were marginal.

4) verify the DRAM, replace if you can, change to slowest
setting posiable (3-3-3-3 or maybe 4-3-3-3). As with the
cache, Linux seems to stress the system more than Win95 or NT

5) I read an article in EE Times which claimed some motherboard
manufactures were cutting the corners with the decoupling
caps used to remove noise from the CPU power supply.
Apparently newer CPUs running at higher clocks generate
enough noise to crash itself unless proper decoupling is
there. Maybe you have one of these motherboards.

6) Finally, verify the CPU in a known system. I have heard
reports of people getting CPUs that will not run at rated
speed. Weather its for above reasons or bad screening on
AMDs part I dont know. Most people (like me) are able to
over-clock the 166 into the 200 range.

hope this helps,
-donnie