Motherboard High temperature

There something in my computer with a high temperature which cause a shut down when playing game.I already tried a lot of monitor temperature and I cannot figure out what is the cause of that.I cannot play game anymore more than 5-10 minute even when I download with utorrent my temperature getting higher.I was wondering if that could be the northbridge or southbridge since that the only temperature I can't see on my monitor and speed fan does show the high temperature in my computer but doesn't tell me what is it temp3?:cry: I really dont know what to do?

My computer set

Motherboard: Gigabyte GA-970A-D3

Proccesor: AMD FX-8150 Zambezi 3.6GHz Socket AM3+ 125W Eight-Core

Ram: G.SKILL Ripjaws X Series 8GB 240-Pin DDR3 SDRAM DDR3 1600

Graphics Card: XFX Double D FX-787A-CDFC Radeon HD 7870 GHz Edition 2GB

Power Supply: OCZ Fatal1ty 750W Modular Gaming 80Plus Bronze Power Supply

Hard drive 1: Seagate Barracuda ST31000524AS 1TB 7200 RPM 32MB Cache SATA 6.0Gb/s 3.5" Internal Hard Drive

Hard drive 2: Seagate Barracuda 7200.14 ST3000DM001 3TB 7200 RPM 64MB Cache SATA 6.0Gb/s 3.5" Internal Hard Drive