BSODs and no signal to monitor

My system specs are following:

Cooler Master ATCS 840 Case

Corsair AX1200 Power supply

Asus P5Q Pro Turbo Motherboard

Intel Core 2 Duo E8500 CPU no OC

Corsair XMS2 8GB RAM

XFX Radeon HD 6870 1GB Video Card

Asus Xonar Essence ST Sound Card

Windows 7 Home Premium 64 bit

I decided to make some upgrades to my PC so I purchased a second video card to crossfire it and another 4GB of RAM (I had 4, now I have 8 as shown in my specs). I received those items two days ago, I installed it and then my new problems began.

First, when I installed the crossfire setup I noticed no increase in performance, actually it was a decrease, so I reinstalled the drivers and the Catalyst Profiles. After the required reboot my sound card wouldn't start the device manager showed an error with that device (Code 10). So I reinstalled the sound card and it's drivers and everything worked again.

Yesterday morning, when I turned on my PC, the videocards weren't sending signal to the monitor. So I tried to turn it on several times, on the 5th or 6th time it finally sent signal to the monitor, and when my desktop appeared I had a BSOD, and again I didn't have signal to my monitor. So I uninstalled the crossfire and tried with the individual cards and in different ports, nothing worked. And again, in one of many attempts it finally sent signal to the monitor. The same happened again when I left my computer off for a few hours.

Sometimes when my PC booted correctly I had a few notification of "windows has recovered from an unexpected shutdown", all reports were from BSODs. Here are the reports:

Problem signature:

Problem Event Name: BlueScreen

OS Version: 6.1.7601.2.1.0.768.3

Locale ID: 1033

Additional information about the problem:

BCCode: 24

BCP1: 00000000001904FB

BCP2: FFFFF8800617E1F8

BCP3: FFFFF8800617DA50

BCP4: FFFFF800024E5A69

OS Version: 6_1_7601

Service Pack: 1_0

Product: 768_1

Files that help describe the problem:

C:\Windows\Minidump\102211-31699-01.dmp

C:\Users\Alejandro\AppData\Local\Temp\WER-60887-0.sysdata.xml

Read our privacy statement online:

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If the online privacy statement is not available, please read our privacy statement offline:

  C:\Windows\system32\en-US\erofflps.txt

________________________________________________________________________________________________

Problem signature:

Problem Event Name: BlueScreen

OS Version: 6.1.7601.2.1.0.768.3

Locale ID: 1033

Additional information about the problem:

BCCode: 50

BCP1: FFFFF88009BFD0B0

BCP2: 0000000000000000

BCP3: FFFFF800028A57DD

BCP4: 0000000000000002

OS Version: 6_1_7601

Service Pack: 1_0

Product: 768_1

Files that help describe the problem:

C:\Windows\Minidump\102211-24476-01.dmp

C:\Users\Alejandro\AppData\Local\Temp\WER-48843-0.sysdata.xml

Read our privacy statement online:

http://go.microsoft.com/fwlink/?linkid=104288&clcid=0x0409

If the online privacy statement is not available, please read our privacy statement offline:

C:\Windows\system32\en-US\erofflps.txt

________________________________________________________________________________________________

Problem signature:

Problem Event Name: BlueScreen

OS Version: 6.1.7601.2.1.0.768.3

Locale ID: 1033

Additional information about the problem:

BCCode: 3b

BCP1: 00000000C000001D

BCP2: FFFFF80002480BC6

BCP3: FFFFF88007E24F60

BCP4: 0000000000000000

OS Version: 6_1_7601

Service Pack: 1_0

Product: 768_1

Files that help describe the problem:

C:\Windows\Minidump\102311-44023-01.dmp

C:\Users\Alejandro\AppData\Local\Temp\WER-76253-0.sysdata.xml

Read our privacy statement online:

http://go.microsoft.com/fwlink/?linkid=104288&clcid=0x0409

If the online privacy statement is not available, please read our privacy statement offline:

C:\Windows\system32\en-US\erofflps.txt

______________________________________________________________________________________________________

Also, in one of the few times that my PC booted up correctly, it asked me to run the "Startup Repair" tool, so I ran it and of course my problem wasn't solved but it showed the following report about the problem:

Startup Repair cannot repair this computer automatically

Problem signature:

 Problem Event Name:                                       StartupRepairOffline

 Problem Signature 01:                                      6.1.7600.16385

 Problem Signature 02:                                      6.1.7600.16385  

 Problem Signature 03:                                      unknown

 Problem Signature 04:                                      217

 Problem Signature 05:                                      AutoFailover

 Problem Signature 06:                                      1

 Problem Signature 07:                                      BadDriver

 OS Version:                                                         6.1.7600.2.0.0.256.1

 Locale ID:                                                            1033

It shows that there is a bad driver, but which could be the bad driver? Perhaps the video card's driver or maybe the motherboards?

I'm starting to think that my motherboard is the issue, since this isn't the first time that I have a hardware problem with this PC, like I show in this thread:

http://answers.microsoft.com/en-us/windows/forum/windows\_7-system/random-blue-screen-when-gaming/642c3633-83a4-4faf-bd1b-103d0fa1cded

Today I had to turn my PC on and off for like 7 or 8 times for it to boot properly. Once the PC is on it works great and I have no problems, also I uninstalled the Crossfire setup since I didn't think all the noise and heat was worth it.

Please help me with this, since this is my study, work and entertainment setup and this problem is so annoying that it'ts making me want to throw my PC from the 4th floor.