I've recently upgraded (believe it or not) to a Pentium 200 MMX chip from an older Cyrix. My motherboard supports this chip, with dual voltage controlled by jumpers. I reset the jumpers (checked and rechecked) to match the Pentium specifications-- 2.8 core, 3.4 I/O. (Actually, my motherboard only offers 2.7 or 2.9 core; I tried both). The problem is that the system hangs hard, requiring a cold boot, after a few minutes of operation. These hangs are obviously electrical in origin, since they occur sometimes before or during BIOS startup, as well as later during Windows sessions. So, I tried upping the core voltage to the next setting of 3.4, and Voila!-- now, no problem with hangs. However-- Yikes! Will this high core voltage setting damage my new Pentium chip? Why won't it run at a core voltage closer to that specified?

Cooling info: a CPU heat sink with fan (4 other fans in case; what's that gray tape on the bottom of the CPU heat sink for anyway?)

System info: JBond motherboard; 66Mhz bus; 96M RAM; lots of peripherals; no problems running old Cyrix P166; Windows 98SE; lots of diagnostic programs (Norton, CheckIT, CPU and motherboard monitors), none of which show any problem; recent power supply replacement; recent BIOS upgrade (Award 4.51).

Intentions: I'm getting ready to overclock the Pentium, but am hesitating because of voltage question.

Thanks for any suggestions.

I wouldn't run the CPU at the higher voltage, it is very possible that it could damage the CPU. 2.7 should work for that CPU. I'm running a P-200MMX and have had no problems with it on 3 different boards.

The gray tape is to transfer the heat to the heatsink more efficiently. You can also get heat sink paste at Radio Shack which serves the same purpose. If you plan on overclocking, I would get some, and make sure you have plenty fans onboard.

I don't recommend overclocking at all, the CPU is tested at the factory, and is marked to run at the speed at which it performs most reliably, and at the best heat range. Overclocking will always bring up heat issues, and very possibly make the system unstable. Higher voltage will cause heat problems too, as well as actual damage to the CPU.

The problem with the system locking up could be in several areas, and is not easy to troubleshoot. I need to post some info on my site, but haven't yet...

Go to Start\Run and type msconfig. Click the Start Up tab and uncheck everything you don't need. You'll need to keep Scan Registry, Task Monitor, System Tray, Load Power Profile, and your virus scanner. Everything else can go at least temporarily. Add them back one thing at a time at each boot, and see if you can isolate which one causes the system to hang. Also check the config.sys and autoexec.bat files, they both are usually empty, but config.sys might have a himem.sys line. Leave it.

after trying that, boot with the F8 key and choose Step by Step Confirmation Press Y for these:
Load Doublespace Driver
Process the System Registry
DEVICE=C:\WINDOWS\HIMEM.SYS
DEVICE=C:\WINDOWS\IFSHLP.SYS
Load the Windows Graphical User INterface
Load all Windows Drivers

Press N for everything else, and see if the system hangs. Add one line at a time until it starts to hang again.

Write down all changes at all times and make any changes one at a time. This makes it easier to change things back.

Check the BIOS settings. Make sure System BIOS Caching and Video BIOS Caching are both enabled. Disabling these is for troubleshooting, and can cause serious performance issues, but you can try it and see if it stops the problem. Make sure Video Pallette Snoop is disabled. Check the Power Management settings, I keep mine disabled in BIOS and let Windows handle it. You might also try setting default values in BIOS and see if that makes a difference.

Can't think of much else right now, I'll post again if I do. Also check the Microsoft Knowledge Database. You'll find a link to it at my site below.



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