Help help help...

System is -
Product Number AMD/AD3870WNGXBOX
Product Desc. AMD A8-3870K BLACK Ed. sFM1
Serial Number 5117342715

Product Number ASUS/CASE/TA881
Serial Number 1816510281

Product Number ATRIX/IOCRD001
Serial Number 3617003663

Product Number ARTIC/ALPINE64/GT
Product Desc. Arctic Alpine 64 GT AMD Cooler
Serial Number 6917338596

Product Number SONY/AD-5280S-0B
Product Desc. Sony AD-5280S-0B 24x DVD˝R
Serial Number 8817220688

Product Number CORSAIR/CMPSU-600CX
Product Desc. CAIR 600W CMPSU-600CXV2UK PSU
Serial Number 4417243444

Product Number OCZ/SLD3-25SAT3-120G
Product Desc. 120GB SLD325SAT3120G SOLID 3
Serial Number 1017297101

Product Number SGATE/ST1000DM003
Product Desc. 1TB SGATE ST1000DM003 SATA3
Serial Number 0017120300

Product Number GIGA/GA-A75-D3H
Product Desc. GByte GA-A75-D3H MoBo

Product Number CM/CMZ8GX3M2A1600C9
Product Desc. 8GB 2x4G CMZ8GX3M2A1600C9 XMP
Serial Number 9717334779

Running windows 7 - keep getting black screen when using the PC and occasionally it forgets the front and or rear USBs. The MB, CPU and Ram have all been back to SCAN who say that they are not faulty. However, when I installed an external graphics card the black screen issue went away. Last night spent hours cleaning everything out - fresh reload of all software and appeared to be ok. Took it home plugged it in and same thing happened again. Any assistance or guidance would really be appreciated. I am sick of the thing. I have the parts since Oct 2012 and used it for approximately a couple of hours in total. Ahhhhh. Cheers. <o:p></o:p>