K7N420 Pro v.1.0 - No support for anything over 100Mhz FSB

Question

I have the MSI K7N420 Pro v.1.0 and I've tried 3 different known good CPUs in this board.  (2 Athlon XP 1700+ and 1 Athlon 1.2ghz).  Both Athlon XPs are designated: AX1700DMT3C, while the 1.2Ghz is designated A1200AMS3C.  I tried several different memory modules from 128MB to 512MB individually and in pairs / and in one memory slot at a time or side-by-side slots.  And two PSUs: 1 250W Enlight and a 500W "off brand".  I have 1 IDE hard drive and 1 CD ROM.  I was able to install Windows once, using one of the 1700+, but then realized that it only registered as a 1100Ghz.  Went into the BIOS and changed it to the proper setting (133/266/66) and it registered as the 1700+.  But soon after the boot the system just goes black and halts.  After a long diagnosis (and updating the BIOS), I've found that when I raise the FSB setting to anything over 100Mhz, the motherboard can't handle it.  What is that all about?  Is this motherboard FUBAR or what?

Answer 1

The high temp. is partly because of the fast memory. It can however get bettered with a reseating of the processor, or rather a better processor heat sink & fan (HSF).
Before you give up, try this:
Reseating time
You need:
a star shaped, Philips screwdriver, and an ordinary flat one
strong, preferably chemical alcohole and/or Acetonic
a tuss of cotton
clean, preferably dust free cloths
thermal grease, preferably Arctic Silver
good light and a large kitchen table
some patience
a vacuum cleaner, preferably reversible, or a can of compressed air is not bad.
Pull the power cable out, and disconnect mouse, keyboard and such cables from the rear.
Put the case with the open side up on the kitchen table or similar. Have a newspaper under to prevent scratches.
Disconnect all cabling and possible AGP- and PCI-cards from the motherboard. It isn't absolutely necessary, but you might as well take the memory out too, as it will give you more freedom later.
With a philips screwdriver /star shaped/ unfasten the motherboard. When lifting it out I normally use the heat sink. Lift slowly.
Put the motherboard beside the case on something a bit soft, a cloth or a thick newspaper. Use an ordinary, flat, screwdriver to unfasten the heat sink. You push a clip down, and when that is loose it's easy to lift the heat sink off.
Clean both the bottom of the heat sink and the processor chip from old thermal grease. This is important! Strong alcohole and oil free Acetonic and a tuss(?) of cotton are good for this. After the cleaning, dry with a clean cloth.
If it is possible, use high-pressure air to blow the heat sink fins free of dust.
Make a note of the model no. on the processor.
Put the processor back on. Add a small drop of new thermal grease on the very chip of the processor. The drop might be half the size of a corn of rice. Spread it out with a plastic card: American Express Gold. 
Make a virtual seating of the heat sink, so you are sure where to finally fasten the clip.
This might sound like a major task, but when prepared you'll do it in about fifteen minutes.
Before putting the motherboard back, you might have a look to see if the case needs some dry cleaning. Also have a look at the PSU and the cards. Don't use anything than air.
Here is some additional, illustrated, guidance:
http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/23986.pdf