Quoted from cfh:
Memory caps work well if you have good/recent RAM. like on older games with 5101 ram (bally -17 and -35/gtb sys80/wms sys3-7), you need the 'new' phillips 5101 for this to really work. For example if you have an AMI 5101, a memory cap just won't work past about 2 days.
WMS for about 1-2 years times stuffed SHIT quality 5101s into their MPUs. They are marked low power, but consume current like a 2101. System 7 era I believe it was. The PCD5101P data sheets indicates it consumes a crazy low amount of current and will hold the contents down to Vcc = 1v.
$6 mem cap vs $10 nvram. Still a no brainer value wise to me (again, im sure im bias =P). SUPERCAPs do fail too overtime. Gamatron daughter boards used a 1F super cap. It held a charge for only about two hours, granted it was 20 years old.
Supercap life expectancy...
"The real application lifetime of supercapacitors, also called "service life", "life expectancy" or "load life", can reach 10 to 15 years or more at room temperature. Such long periods cannot be tested by manufacturers. Hence, they specify the expected capacitor lifetime at the maximum temperature and voltage conditions. The results are specified in datasheets using the notation "tested time (hours)/max. temperature (°C)", such as "5000 h/65 °C". With this value and expressions derived from historical data, lifetimes can be estimated for lower temperature conditions."
FM16W08 endurance at constant R/W at 1 mhz is like 180 years.