|"installed in a Power Up case w/ 450 W power supply"...."bought a new Diablotek 500W supply"...."What the heck??"|
You simply have poor taste in power supplies. It's not necessarily about the wattage, it's about the amperage & the quality of the components used within the unit. You couldn't pay me to use a Diablotek PSU. Read this JonnyGuru review/conclusion of the 1050W unit:
As for the 20-pin vs 24-pin plug, are you running a PCIe x16 video card? The extra 4-pins supply power to the PCIe x16 slot. If you're not running a card, the extra 4-pins aren't absolutely necessary but I highly suggest you get a decent power supply before you fry your entire system.