issues with asrock 990fx killer

It means that your FX-8350 supports RAM clock speed of 1600 MHz with four sticks only if it's single rank memory. If it's dual rank (couldn't find out if it is or not), the highest supported RAM clock speed is 1333 MHz.

The point of running the test isn't really to solve anything. Since your problems may be memory related, I just think it would be a good idea to double-check that the RAM is working as it should - if lowering the RAM speed helps, that is. You can of course run it in any case. If it makes your system crash, maybe the logfile will give you some additional insight on the root cause of the instability.

Ah yes, you had tried the memory from that FX-4300 and it didn't improve the stability. I did some further digging and the G.Skill sticks do in fact seem to be single rank, so 1600 MHz should be okay. The limitation is not caused by the motherboard, it's caused by the FX-series memory controller (CPU-NB), which is why all FX-series CPUs have the same limitations regarding RAM speed. Just to ensure we're on the same page, I'll further point out that CPU-NB and NB are not the same thing: CPU-NB is the memory controller of your CPU while NB is the nortbridge chipset on the motherboard. It's the CPU-NB that you have overclocked, so if something is broken, it should be the CPU.

You could check the motherboard by swapping your FX-8350 for your wife's FX-4300, but that of course is a bit labour intesive... Even though you have a kit of four RAM sticks, I'd first try using only two at a time to see if that has an effect. Also, have you checked your system's temperatures and voltages with HWMonitor? Are you running your system at stock speeds at the moment?

i looked in my bios and i did over clock the CPU NB but not the cpu nb voltage which was set to 1.150v

That may be a good way to isolate the issue. I'm not surprised you had stability issues running the CPU-NB at those speeds on stock voltages, but I've no idea if and how that could actually damage the IMC. Increasing the clock speed without changing the voltage doesn't increase the head load that much and since the CPU-NB is located on the die, your CPU cooler should have been able to handle it.

Have I understood correctly that your system occasionally crashes even when you're not doing anything on it? You're not running Seti@home, Folding@home or anything similar? If the system crashes when it's basically idle, that's not exactly a good sign. Your temperatures and voltages are still a question mark. Have you checked both using HWMonitor? How high are the CPU and socket temps at idle and under load? What sort of case cooling do you have?

Those temps do seem a bit high. For gaming 140F should be okay, but it's still over the often recommended 130F maximum temperature under stress testing. Even though an FX CPU may be able to take higher temperatures than older Phenom II's, your system might still not be fully stable under Prime95. Also, at idle I would've expected something around 85F, especially since there should be no issues with the case cooling. Maybe the TIM between the CPU and the heatsink is getting old or has not spread properly...

Btw, the motherboard temperature and socket temperature are two different things. The socket temperature is the CPUTIN temperature in HWMonitor and for that the often recommended maximum temperature is 158F, but again the FX CPU might be able to stay stable even at 185F. See here, for example:

http://www.overclockers.com/forums/showthread.php/728489-FX-its-tougher-than-you-think

While your temperatures are a bit higher than what I would have expected, I don't think they're what causing the crashes. At idle even the VRM should be running cool enough. If you know of a way to make the system crash (like running Aida's stress test), you could try bumping the CPU-NB voltage slightly and see if that has an effect on stability. Also bumping the RAM voltage slightly might be worth a try, it seemed to help for someone experiencing similar issues (it might be worth reading the whole thread):

http://www.xtremesystems.org/forums/showthread.php?284441-strange-stability-issues-with-FX-8350

I'd probably start with bumping the RAM to 1.55V and then 1.6V if that doesn't help. If that's not enough, then I'd try 1.2V for the CPU-NB and 1.55V for RAM, and then again increasing RAM voltage to 1.6V if it still doesn't work.