See here.
Hardware watchdog driver for the AMD/ATI SP5100 chipset.
sp5100_tco is an AMD specific watchdog module. I very much doubt that this advice will be helpful to anyone with an Intel processor.
If you want to blacklist watchdog modules, you really need to determine what modules are in use on the system. Just blindly blacklisting random modules until something works is not a very efficient way to go about things.
You could try running something like this:
lsmod | grep -e dog -e wdt -e tco
This will look for the most common watchdog modules that are used for Intel or AMD processors/mobos. Once you see what module(s) are in use on your system, then you can blacklist them.