I just want to preface this post by saying that I wholly apologize if this has been covered anywhere in this thread previously, but ~500 pages of posts to search through is extremely rough.

Anyway, I just purchased a used S3+ that arrived a couple days ago and I'm still figuring it out. My previous experience with mining lies wholly with small scrypt rigs and Pi controllers. I'm only a about 6-7 months into mining (late start, I know), but I'm picking up on things rather quickly. Regardless of my mini-scrypt rig experience, I'm struggling to get my S3+ to hash over 500GH, when it was advertised at a stable 566+GH when I purchased it from fleabay. To provide another tidbit of info, I'm using a 650W PSU to power the S3+, so I'm rather sure I'm providing enough power to the unit.

Anywho, to the main point of my post: My S3+ is currently running the latest firmware and started with the factory defaults (from Jan2015) which includes the 4.6.1 version of cgminer built for the S3 machines. I'm currently using a setting of 275MHz, and 815 voltage. However, I'm looking to include xnonce support while overclocking my S3+. This presented complications for me as soon as I began looking into it. I started by installing the cgminer 4.7 provided by westhash/mintsy/etc for S3 rigs that includes xnonce support. The problem that arises when using the provided "updated" version is that the '--bitmain-voltage' command line option no longer seems to work with this version, thusly cgminer fails to start unless I remove this specific option from S99cgminer's "PARAMS=" line. To further my inquiry, I am curious as to if/how I can get the latest cgminer version (4.9.2, or any version for that matter) working properly with xnonce support AND voltage options with my device, if at all possible.

I would greatly appreciate and welcome any advice on the matter as I am a complete noob when it comes to Bitmain devices and updated versions of cgminer (my scrypt rig uses a really old dmaxl fork of cgminer). Treat me like a complete idiot and berate me for all I care, as long as it helps me maximize the output of my device (aiming for at least a stable 500+GH). Feel free to ask me for anything to help you help me.