Random system freezes for weeks

Update:
Yesterday I installed the anniversary update with some hope that the update would resolve the problem, unfortunately it didn't.
I had about 5-10 freezes yesterday with a little odd pattern. Every 3-4 hours a freeze would occur, then after a reboot a freeze occured within a few minutes, and back to 3-4h.

I've kept driver verifier running with all settings enabled on all available drivers, unfortunately it turned out that no single driver caused a BSOD, but freezes kept occuring in an increasing frequency.

Currently driver verifier is disabled and I have removed a lot of programs.
My system has been stable for 8-9h today, until I installed my music program. After a short period of my music program being installed a system freeze occured, so it is currently removed again.

It'll take me some time to reinstall everything and find any other programs causing freezes as it'll be around 100-150 programs.

I took the risk of installing everything except for my music program and it looks like it's fine since there hasn't been a system freeze in a time where several freezes would've occured a few days earlier.

Update:

Unfortunately my system had last thursday a huge amount of system freezes, so I prepared to perform a clean install of Windows 10 1607, backed up everything that wasn't a program and removed my HDD from the system before doing the clean install.
I left the system running for a day, when I got home from my internship I saw the system froze a minute after I left in the morning. A system freeze with only my SSD connected doesn't sound logic to me for some reason, so I bit another bullet and performed a clean install of Windows 10 1511. After 3 days and a few reboots resulting in a stable system I reconnected my HDD whereafter about 20 minutes a system freeze occured, as this installation is almost a vanille installation (drivers from Gigabyte are installed) where the only change is a HDD there are 3 options for the cause of this freeze:
1. Faulty motherboard connection, if I remember correctly I've been using this connection for a long time.
2. Bad cables
3. HDD itself

Currently I've switched the HDD connection, I hope this is the root cause because else I may need to buy some extra cables or RMA the HDD.

To provide another update, both my SSD and HDD froze after a day of a clean install with different cabling.

Currently I suspect the CPU as the cause, because under the CPU there looks to be a small part giving a different reflection when holding it in a certain angle against the light.

As I'm no hardware specialist I'm going to let a few experts close to my living have a look at it before I RMA the CPU.

Alright, here is a final update after months.

Due to personal circumstances it took a while to get to the experts I meant. FYI, these experts worked in a shop called ReplaceDirect. This shop repairs and sells a lot of stuff for smartphones and laptops.

I personally went there for the 2nd time in years and noticed that the experts don't work there anymore. Instead there was a foreign tech guy (from his accent) who I think didn't quite understand me, he kept blaming the GPU for the cause while I tried to explain that the GPU was installed months after the issue started. After a (nice?) conversation they said there wasn't anything they could do, they only repair smartphones and laptops because they have the equipment for that. He mentioned that he could run software tests to diagnose the issue, which I already had done tons of times, but nothing more.

After I finally came back home, I decided to first prepare a RMA for the motherboard instead, from what I read about similar issues the motherboard is more often the cause than the CPU. I went to the Gigabyte support page for my motherboard and noticed that after 8 months 3 BIOS updates were released. 2 BIOS updates are released to provide support for the 7th generation of CPUs and 1 of them for improving VGA compatibility. I thought that installing the newest update may help something. So, I downloaded the BIOS, booted into the BIOS and made a BIOS backup first, then I installed the update and booted into Windows.

The first impression I had was that Windows somehow became extremely laggy. In The Witcher 3: Wild Hunt I would usually get around 50-60 fp/s, this time it was between 20 and 40. Even while doing nothing the system was extremely laggy. I booted into safe mode to find out if the lagging also existed there, fortunately this wasn't the case.
I decided that my next move was to clean install Windows, after backing up everything I didn't want to loose and so I did.
A few hours after a clean Windows I was mainly done with installing all stuff (programs, drivers, customization where I wanted, games).

After reinstalling Windows and everything, I noticed 2 issues I didn't like.
1. The EFI partition was on the HDD, while I installed Windows on the SSD, partitioning was kind of a chaos
2. The HDD partitions appeared to be a dynamic disk.
To solve the dynamic disk issue, I downloaded the recovery tool from @Kyhi and used Minitool Partition Wizard to easily convert the dynamic partitions to basic.
To get the EFI partition on the correct location, I deleted the partition from the HDD and disconnected it. Then I wiped the SSD and again clean installed Windows on it.
The EFI partition was most likely installed on the HDD, because the HDD was seen as Disk 0 by Windows, so I switched the sata ports between the SSD and the HDD so the SSD is now seen as Disk 0.

I wiped the SSD on the 17th for the last time and have had no single issue since. I have finally been able to do all the things for which I had built the system.

The final blame looks to be BIOS version F3, I have no idea why but I guess it was some kind of a bug with it.

axe0 said:

Alright, here is a final update after months.

Due to personal circumstances it took a while to get to the experts I meant. FYI, these experts worked in a shop called ReplaceDirect. This shop repairs and sells a lot of stuff for smartphones and laptops.

I personally went there for the 2nd time in years and noticed that the experts don't work there anymore. Instead there was a foreign tech guy (from his accent) who I think didn't quite understand me, he kept blaming the GPU for the cause while I tried to explain that the GPU was installed months after the issue started. After a (nice?) conversation they said there wasn't anything they could do, they only repair smartphones and laptops because they have the equipment for that. He mentioned that he could run software tests to diagnose the issue, which I already had done tons of times, but nothing more.

After I finally came back home, I decided to first prepare a RMA for the motherboard instead, from what I read about similar issues the motherboard is more often the cause than the CPU. I went to the Gigabyte support page for my motherboard and noticed that after 8 months 3 BIOS updates were released. 2 BIOS updates are released to provide support for the 7th generation of CPUs and 1 of them for improving VGA compatibility. I thought that installing the newest update may help something. So, I downloaded the BIOS, booted into the BIOS and made a BIOS backup first, then I installed the update and booted into Windows.

The first impression I had was that Windows somehow became extremely laggy. In The Witcher 3: Wild Hunt I would usually get around 50-60 fp/s, this time it was between 20 and 40. Even while doing nothing the system was extremely laggy. I booted into safe mode to find out if the lagging also existed there, fortunately this wasn't the case.
I decided that my next move was to clean install Windows, after backing up everything I didn't want to loose and so I did.
A few hours after a clean Windows I was mainly done with installing all stuff (programs, drivers, customization where I wanted, games).

After reinstalling Windows and everything, I noticed 2 issues I didn't like.
1. The EFI partition was on the HDD, while I installed Windows on the SSD, partitioning was kind of a chaos
2. The HDD partitions appeared to be a dynamic disk.
To solve the dynamic disk issue, I downloaded the recovery tool from @Kyhi and used Minitool Partition Wizard to easily convert the dynamic partitions to basic.
To get the EFI partition on the correct location, I deleted the partition from the HDD and disconnected it. Then I wiped the SSD and again clean installed Windows on it.
The EFI partition was most likely installed on the HDD, because the HDD was seen as Disk 0 by Windows, so I switched the sata ports between the SSD and the HDD so the SSD is now seen as Disk 0.

I wiped the SSD on the 17th for the last time and have had no single issue since. I have finally been able to do all the things for which I had built the system.

The final blame looks to be BIOS version F3, I have no idea why but I guess it was some kind of a bug with it.

Hopefully that was it. Good to hear you have it sorted out.