BSOD -> :'(

Go to your BIOS, DRAM timing settings and change the 'Command Rate' from 1T to 2T.
This will help the RAM stability.

Run memtest86+ for minimum 7 passes, best to run overnight.

Let us know how the the tests go.

Can you fill in your system specs, in the lower left corner of any of your posts, "My System Specs". Include as much detail as you can.

Check that you didn't bump any cables on your motherboard, check that all of them are tight.
If the CPU fan power cable came loose, the computer won't boot, check it.

If I understand correctly, you install another HDD and it wouldn't boot, you took that HDD out and it still wouldn't boot, is this correct?
Double check the hard drive cables, disconnect them check them and re-connect, make sure you have the OS drive in port0.

You had it correct there. Had a dvd writer and my OS hdd on a sata-600 port, but it seems I switched them. Put the writer in a sata-300 port, the hdd back in the first and now it works again!.
Having quite some BSOD's right now btw, I'll upload the dumps in a sec. I'll also change the command rate.

I can't seem to find any command rate settings, could it have a different name?
Also, I noticed the last dmp file has a april 17 date, it seems no new dmp are created?
Some BSOD's i got:
PFN LIST CORRUPT
SYSTEM SERVICE EXEPTION
MEMORY MANAGEMENT
and one about fltmgr.sys

Also, is there any chance it could be a hardware issue? Memtest always passes, but somehow is suspect it to be a motherboard error. Even though I appreciate the effort you're putting into this, a brand new pc bought under 1,5 month ago causing nothing but errors, bluescreens and usb issues with over a dozen windows installs just doesn't seem right to me. I'd like to rule things out now.

It can be caused by hardware,

Run Data Lifeguard Diagnostic for Windows

Also take a look at this: WD Caviar Green HDDs Suffer from a Critical Design Flaw


For the command rate, got to Advanced DRAM Configuration > Command Rate2

CPU - Stress Test with Prime95
Prime95 Torture test
If memtest86+ passes then run Prime95 torture test.
First open CoreTemp to monitor CPU temperatures, don't go over 77degC.
Open Prime95 and stop the test, in Advanced tab select 'Round off checking', in the Options tab select 'Torture Test...', in the window that opens select 'Blend', after 'Number of torture test threads to run' enter 4, then click OK to start the test.

This will run your CPU at max frequency. Watch the core temps until they level off.

Ok, let us know the results.

Just set the command rate to 2T. Had to change DRAM Timing Mode to either Link or Unlink (set it to Link) to be able to enter advanced dram setting. Also had 3T optional, does this matter?
Also changed the idle settings of the hdd. About to run memtest again overnight. Also, just had an BUGCODE_USB_DRIVER on win7 again, and somewhat later even a MEMORY_MANAGEMENT bluescreen. And the C:\windows\minidump folder doesn't contain any dmp files newer than april 17, something I turned off?
Ran the prime95 test, didn't go over 57 celsius. I'll come back with the memtest results.
Just had a look at the MSI test results, and my memory isn't listed, just like my PSU or graphics card. Does any of this matter?