Is it really overheating, bad sensor, or another problem?

I received an iBUYPOWER NE690FX for Christmas of 2013 which has had the following modifications...

Stock 300 Watt PSU replaced with a Lepa N500
8GB OEM RAM (ADATA) upgraded to 16GB Kingston HyperX (4GB x 4)
Replaced NZXT case with Thermaltake V4 Black
Added Rosewill internal card reader & USB 2.0/3.0 Hub
120mm intake fans 1 front, 1 bottom, & 1 side
120mm exhaust 1 top, 1 rear

Other Specs:

Gigabyte GA-78LMT-USB3
AMD FX-4130 w/OEM Thermaltake H/S Fan
eVGA GeForce GT610
W/D 1TB HDD
DVD Burner

F/F to January this year I wiped the drive with DBAN, repartitioned the drive & reinstalled Win7 HP. While reinstalling some of my other software there was an awful noise which turned out to be the CPU overheating (I had to hold the power button to shut it down).
I replaced the OEM H/S Fan with the stock H/S Fan that came with an AMD FX-8350 using Arctic MX-4 thermal paste. Then used OpenHardwareMonitor & an earlier version of Core Temp to monitor temps. I began getting overheat alerts from Core Temp and it was putting the computer to sleep. So, I bought an Arctic Freezer 13 and installed it. For over 3 weeks it ran almost constantly never shut down for more than a couple of minutes while I used it to run everything it would ever need to do except internet (I actually tried to overwork it). Then one morning I noticed it had been put to sleep by Core Temp for overheating again. There was a notification in the taskbar telling me that core 3 was at 256 C (493 F), Core Temp had crashed ("stopped working and needs to close"). Since then it has happened several more times like that. The 2 times it happened while I was in the room, there was no audible warning. There's no discoloration indicating temps that high, the back of the motherboard was only warm to the touch yet it reported core 3 running at 256 C. That was with an earlier version of CoreTemp (v. 0.99.*). That computer now has the following: Core Temp 1.0 RC6, Open Hardware Monitor, Speccy & CPUID HWMonitor. I took several screenshots of 3 of these at bootup, while working, (compressing video files) and when finished.

Could the sensor have been damaged the only time I know for sure it overheated? Is there an issue with that early version of CoreTemp? Should I try another AM3+ motherboard (I have an ASUS M5A78L-M LX Plus). I'm out of ideas. I can give you just about any additional information that doesn't require me to go on the internet with that PC. Both side panels have been off since I replaced the OEM H/S Fan.

Final question...where do I go for help with a Windows XP problem?

LeonDroid said:

Then one morning I noticed it had been put to sleep by Core Temp for overheating again.........................Could the sensor have been damaged the only time I know for sure it overheated....................Is there an issue with that early version of CoreTemp?

I have very little experience with Core Temp.

Can it, on its own, shut down a PC that it thinks is too hot, even if it isn't true?

In normal operation, when things are "OK", do the temps reported by Core Temp match the temps reported by at least one other temp monitoring application?

If you disable or uninstall Core Temp completely, do you still have issues?

The temps of plus 400 Fahrenheit surely must be wrong if you see no sign of damage.

You describe "an awful noise which turned out to be the CPU overheating". I don't know that overheating by itself would necessarily make any particular noise. I'm wondering if there was some as yet undetected hardware failure at that time, which resulted in overheating.

I wouldn't expect the cooler swapping to make any significant difference, assuming they were properly mounted and the fan was spinning, as long as the PC is under a reasonable load.

Does your motherboard look perfectly normal, including capacitors?

Can you swap in another power supply?

First, in the options menu of Core Temp, there are overheat protection settings which can be set to put the computer to sleep, hibernate, or shut down at a specified temp but it has to be enabled.

I forgot to post screenshots of the 3 system monitoring programs earlier. I'll do that now. They are all within a degree or two of each other.

Core Temp is the only one that shuts everything down in case of overheating so I hate to uninstall it. However, I removed the earlier version and then installed the newest release in case that was the issue.

I'm sure the noise I heard was an alert from the motherboard. The motherboard looks normal. However the capacitors to the left of the CPU are mostly obstructed by some kind of passive cooler and the Arctic Freezer fins. I gave it a once over when I swapped out the cooler because I needed to replace the brass standoffs with non conductive alternatives.
That actually reminds me that there was an issue with ESD. The computer would freeze or restart any time there was a shock when I touched it. Gigabyte tech support suggested using non conductive standoffs, fiber washers, and/or grounding the case directly to an outlet.

Swapping out the PSU at this time is not possible because I don't have a spare one that will work yet.

Honestly, I've had tunnel vision on the temperature problem, and never thought to check the voltages, so I never even noticed.

Layback Bear: The power supply is the first on my list of upgrades...Lepa N500.
This one: http://www.newegg.com/Product/Produc...-002-_-Product
It's still under warranty if I need to replace it.

The computer was asleep again when I got up this morning. Attaching 2 more screenshots.

The multiple hardware monitoring programs are suggested in this and other threads. They only vary by a degree or 2 and I attribute that to differing sample rates and times. Core Temp is the only one I usually run & the one that puts my computer to sleep. The only noticeable difference now is that it reports core 1 as the one overheating instead of core 3.

To be clear, are you suggesting I try a new power supply?
Newegg has this one on sale with a $20 rebate: CORSAIR CX series CX500 500W ATX12V v2.3 80 PLUS BRONZE Certified Active PFC Power Supply - Newegg.com

Or, I can save $10 with this one: CORSAIR CX series CX430 430W ATX12V v2.3 80 PLUS BRONZE Certified Active PFC Power Supply - Newegg.com I don't think the 5 Amps on 3.3V or the 6 Amps on the +12 will make much difference on this build.

I can't afford the AX series. A little more is ok, but they're 4x more.

Normally Core Temp is the only monitoring program I run, but I'll uninstall it and run just one of the other 2. there should be something for me to put a load on the CPU with tomorrow. I don't do any gaming except the downloadable casual games from sites like BigFish. Plus, a little audio/video conversion and/or compression so I'm not putting that much of a load on the processor at any time. The highest temp I've ever seen while doing that was 29 C (85 F).

I bought a new power supply. I should have it here, installed and tested by this time next week. I'll post then with the results.
The other will be RMA'd and the replacement saved for a spare.