My question of course is of the Dynex 400W power supply. My first PSU change was when the original blew, my box was still under warranty and they tossed in a Dynex 400W power supply probably because it was the cheapest they had in stock. This PSU has since failed and was showing odd behavior, it would and could boot up both on 115/230 settings the only problem was that only one would run stable and would eventually fail at which time the other setting would now magically be fixed (endless cycle where after one would fail the other would work). Dont ask me how or why but when it finally blew after which my warranty was now expired i replaced with another Dynex 400w thinking (not knowing) that it should do. Recently after another power outage this new psu is seemingly back to its old game although it will now run on both no matter what (before only one would work at a time) except that the one that doesnt work allows boot for 20minutes before failing and turning off. Anyone know why this would be happening or is this just one of those odd coincedences and should just invest in a new psu. I do plan on building a new box later in the year as a christmas gift to myself but would like to keep this box as well.
On the upside the switch controls a voltage doubler circuit and setting it to 230 when the mains is 115 has far less disastrous consequences than doing that where the mains are 230 and you set it to 115 since 230 simply disables the doubler circuit, if you do it where the mains are 230 you now have 460 volts popping out of that circuit obliterating the insides. While it is far less dangerous to do it with 115 V mains, it does still hurt the PSU, and since you are having issues it is safe to say its dead or soon will be.
This time around, i suggest moving into the modern era and get a PSU with APFC(aka no little red switch) and some decent efficiency. Dynex is the best buy house brand, super cheap and not meant to last. Throw that PSU in the trash and get a good little unit from newegg. For your system specs something like the Corsair CX 430 V2 would do fine. http://www.newegg.com/Product/Product.aspx?Item=N82E168...
While it is far less dangerous to do it with 115 V mains, it does still hurt the PSU, and since you are having issues it is safe to say its dead or soon will be.
While the PSU might (sort-of) work off 115V with the switch on 230V, the abnormally low input voltage for the transformer drivers which are designed to operate on ~350VDC will cause the PWM controller to operate at extreme duty factors similar to full load under brownout conditions which the PSU likely is not intended to support on a continuous basis.