Loud GPU fan noise at first boot and then CPU got shut down

Hi all experts,

Recently in 2 weeks ago, I have problem with my CPU.
My CPU is custom and I bought it a year ago. I only use it for online gaming, and sometimes watching movie.

Here are the symptoms:

First symptom:
When I boot my computer for first time of the day in the morning, loud GPU fan noise can be heard. Booting process continues until I can see my desktop. A few minutes and I got an error message that looks like memory address and my CPU got shutdown by itself, monitor LED is on standby. I can't capture the error message because my CPU got shutdown after it appears for 1 second.
I press Reset Button, my computer boots, no loud GPU fan noise and I can use the computer without any problem until night.

Second symptom:
When I boot my computer for first time of the day in the morning, loud GPU fan noise can be heard. Booting process happened for 3 seconds, I don't even see Gigabyte logo when booting and my CPU got shutdown by itself, monitor LED is on standby.
I press Reset Button, my computer boots, no loud GPU fan noise and I can use the computer without any problem until night.

I thought my PSU is the problem, so I went to replace my PSU from Thermaltake Lite Power 600W with Seasonic SS-600ET 600W.
After replacing PSU, I got 2 days of normal use without any loud GPU fan noise or monitor LED on standby. On 3rd day, I got 2nd symptom happening again.

And I thought my GPU is the problem, so I gave my GPU HIS Radeon 7850 2GB DDR5 IceQ X to service center. After one week I got it back and they say, the GPU works perfectly.
I put my GPU back to CPU and I got 2 days of normal use without any loud GPU fan noise or monitor LED on standby. On 3rd day, 1st symptom and 2nd symptom happen again.

1st symptom only happened twice, and 2nd symptom happened everyday.
When 1st symptom happened, I managed to use HWMonitor to see if my CPU got overheated. I was surprised to see that HWMonitor detected my GPU but it has 0 temperature (my processor and motherboard have around 30-40 Celcius temperature).

After 1st or 2nd symptom happened and I can use my computer normally, I use HWMonitor again and it shows that my GPUS has 38 Celcius temperature. I really think overheating is not the cause of my problems.

I'm really clueless what's wrong with my CPU considering these symptom happen only on first boot of the day.

Below is my current computer spec:
OS : Windows 7 Ultimate 64-bit
Processor : Intel(R) Core(TM) i5-3570 CPU @ 3.40 GHz (4 CPUs)
RAM : Corsair CMZ8GX3M2A1600C9 4GB x 2
Display : AMD Radeon HD 7850 2GB DDR5 IceQ X
Motherboard : Gigabyte GA B75M-HD3
HDD : Western Digital Blue WD5000AAKX 500GB
PSU : Seasonic SS-600ET 600W

I could really use any help here.

Thank you.

Edit:
When I gave my GPU to service center, I got a loan of an old Radeon 5560 or so, dont really remember the series.
So, I use it for a week, no symptoms appeared so I'm sure that my GPU is broken.