There are two revisions of the Viper board. One with the IDE port populated and a newer BIOS, and one standard with IDE headers removed. Aside from that, everything is identical. The only known games that have the IDE port populated are ParaParaParadise and Mocap Golf. It is confirmed that you can use a Mocap Golf PCB to replace a bad ParaParaParadise PCB as long as you swap the security chip. It is probable that the same repair works in the other direction.
All other games are theorized to be compatible with each other as long as the security chip is transplanted. There is no currently known way to populate the headers to use a standard game with PPP or Mocap Golf.
The security chip sits just below the RTC-RAM chip and appears at first glance to be a standard 3-leg transistor. Examining the part number reveals it to be a 1-wire EEPROM chip containing the security of the system. It can be transplanted to another board without harm given careful soldering technique.