Strange system monitoring behavior

Hello everyone.

Let's start with my system's specs:

MB: ASRock Z68 Extreme7 Gen3
CPU: Intel Core i7-2600k (non-overclocked)
PSU: OCZ ZT Series 750W Fully Modular
RAM: G.Skill Ripjaws Series XF3-17000CL9D-8GBXM (8GB DDR3, underclocked @1600 MHz, 1.5v)
HDDs: WD5000AAKX (500 GB, SATA 6 GB/s, 7200 RPM)
WD1600AAJS (160 GB, SATA 6 GB/s, 7200 RPM)
OS: Windows 7 Ultimate x64
Optical Drive: Pioneer BDR-206DBK (Blu-Ray burner)
Case: Cooler Master Storm Enforcer
Screen: HP 2311x


Monitoring tools: Piriform Speccy, ASRock Xtreme Tuner, BIOS H/W Monitor


I normally use the rig described above in a really hot environment (33-40 ºC with no A/C) so last week I bought a pair of these to improve the system's cooling. On Saturday afternoon, I installed them as air intakes on the upper opening of the Storm Enforcer. That would make a total of 4 chassis fans all connected to the Motherboard in the following fashion:


Frontal intake fan (200) mm - CHA_FAN1
Rear outtake fan (120) mm - CHA_FAN2
Upper intake fan (120) mm #1- CHA_FAN3
Upper intake fan (120) mm #1 - PWR_FAN


Then I spent a few hours doing some cable management to further improve the airflow. This was all done in much cooler room (25-30 ºC). Once I was finished, I plugged everything back in place and turned the PC on (while still in the cooler room). Everything seemed to be OK. Working temps were lower (35-40 ºC for the CPU down from 42 while idle, 32 ºC on the MB, 30ish for each HDD) and all meters were working just fine.

Shortly after, the screen started to occassionally flicker while randomly showing some noise/garbage. I turned off the whole machine right away and moved it back to my room.

After a few minutes, I turned it on again and launched the UEFI's H/W monitor. To my surprise, it was displaying CPU temps of around 70 degrees and going up. Turned it off again, opened the case and launched the UEFI once more. It showed me the high temps again but no part of the case felt that hot when I moved my hand around it, neither did the air flowing inside of it. I let the machine boot into Windows and all looked fine. No flickering, garbage, etc. When I launched Xtreme Tuner, the temps meters were displaying strange values again; negative numbers this time.

I tried to shutdown the rig so I could check the cables out. When I did this, Windows and the HDDs went off as usual but the MB and all the 5 fans (CPU one included) remained on. I had to press the power button for 5 seconds in order for everything to turn off.

Then I unplugged the new fans and installed the original ones as I had them before. Same thing, wrong values for MB temps and incomplete system shutdowns. Checked the cables again, making sure nothing was misplaced and it all seemed OK. I also reverted some of the cable management I had done but still, same situation every time I booted the machine.

On Sunday, I decided to plug all 4 chassis fans directly into the PSU and after a some more wrong temp displaying & incomplete shutdowns, the machine suddenly started to work just fine all on its own.

I've booted it around 5 more times since then with no issues at all. Now both XTuner & Speccy display their info accurately again. I should mention that during the hiccups, nothing else went wrong in Windows. No hang ups, loss of performance, data corruption or anything similar. Also, Speccy was able to display the temps for CPU & both HDDs as normal.

I'm still extremely puzzled though. Can anyone savvy enough tell me what the hell happened and what are the usual reasons behind/implications of cases like this?

Thanks in advance. And sorry for the wall of text.