IBuyPower

So i bought my ibuypower computer like a year ago and this is gonna be my 3rd time sending it in because when i turn my room light on it turns on.Then i play games the monitor would just turn black,Its Also slow NOTE i only have steam installed and finally i would get blue screens. here is my build and any help would be really nice.

1 x Case NZXT Tempest 410 Elite Gaming Case - Black
1 x Processor Intel® Core™ i5-4670K Processor (4x 3.40GHz/6MB L3 Cache) - Intel Core™ i5-4670K
1 x Motherboard Gigabyte GA-Z87X-D3H *FREE Upgrade to GA-Z87X-OC Force*
1 x Memory 8 GB [4 GB x2] DDR3-1600 Memory Module - Corsair or Major Brand **FREE Upgrade to DDR3-1866 ADATA XPG V2**
1 x Video Card NVIDIA GeForce GTX 780 - 3GB - Single Card
1 x Case Lighting None
1 x Power Supply 850 Watt - AZZA Dynamo 850W
1 x Processor Cooling Certified CPU Fan and Heatsink - [Intel]
1 x Primary Hard Drive 2 TB HARD DRIVE -- 64M Cache, 7200rpm, 6.0Gb/s - Single Drive
1 x Data Hard Drive None
1 x 2nd Optical Drive None
1 x Optical Drive 24x Dual Format/Double Layer DVD±R/±RW + CD-R/RW Drive - Black
1 x Sound Card 3D Premium Surround Sound Onboard
1 x Speaker System None
1 x Network Card Onboard LAN Network (Gb or 10/100)
1 x Monitor None
1 x Keyboard iBUYPOWER Standard Gaming Keyboard
1 x Operating System Microsoft Windows 7 Home Premium + Office Starter 2010 (Includes basic versions of Word and Excel) - 64-Bit