alexo wrote:Can anyone tell me what configuration will require the 500W (or even the 600W) model and what will do nicely with the 430W?
Also, which will be quiteter at the same (<430W) loads, the S12-430 or the S12-500?
Very few configurations are likely to requires a 500W or 600W PSU. Perhaps a Dual SLI or Dual CPU configuration would need this amount of power. If you haven't already, read through the section on typical power draw in our PSU fundamentals article
Depending on the revision you get, the noise levels of the 430W and 500/600W are either too close to call, or the 430W is quieter. The older revision of the 500/600W models used fans that were noticeably louder than the fan in the 430W model. The new revision has eliminated this difference for the most part.
Raymond: It sounds like you've already read through all the information that we know about the differences between the bulk and retail versions. I don't know if anybody here has purchased the bulk 500W version, but I'd expect the differences to be similar to those at the 300W level.
Off the top of my head, I recall that the bulk versions have different/shorter cable configurations, use a stamped metal grill, and do not ship with retail accessories (20->24 pin adaptor, cable management ties, manual, power cable, etc). If you want more specific information, I suggest contacting the retailer you're buying from since they will be able to answer specific questions.