>Random shutdowns< while playing online MMORPG game Tibia

[Obaaan]

I've been using this new computer for about 1-2 months?
And now I tried to play one of my old favorite games Tibia! But the thing is I can only be online and play for like between 10 minutes to 3 hours then my computer just completely shuts down..
I've tried running the game in the three options there is
Directx5, Directx9 and OpenGL
But none of them seems to be any better than the other
Directx5 makes the graffic look like shit, Dx9 makes it crash after some time and OpenGL felt like it crashed even earlier!

My computer build:
AMD FX 8150 8-core processor (3.6ghz)

Kingston DDR3 HyperX PnP 1600MHz 8GB
Kit w/two HyperX 2GB DDR3, CL9-9-9-27

Western Digital Caviar® Black 1TB
SATA 6Gb/s (SATA 3.0), 64MB Cache, 7200RPM, 3.5",
Dual processor

MSI 990FXA-GD65, Socket-AM3+
ATX, 990FX+SB950, DDR3, 2xPCIe(2.0)x16, CFX&SLI,
SATA 6Gb/s, USB 3.0, UEFI

Corsair SSD Force Series GT 120GB 2.5"
SATA 6 Gb/s (SATA3.0), 555MB/515MB/s read/write,
85k IOPS(4k aligned), w/bracket

Gainward GeForce GTX 570 1280MB PhysX
PCI-Express 2.0,"Goes like Hell - GLH", GDDR5, 2xDVI,
HDMI, DisplayPort, 800MHz

Cooler Master GeminII SF524 CPU Kylare
755/1155/1156/1366, AM2/AM2+/AM3/AM3+/FM1,
800~1800 RPM, 34~78 CFM, 15~31.6 dBA
(I didnt want my new good looking CPU to get overheated)

Cooler Master MegaFlow 200 Röd LED Fläkt
200 x 200 x 30mm, 700 RPM, 110 CFM, 19 dBA, 3
Pin, 3-4 pin Adapter
(Even more to cool of my new computer)


And I've tried updating my grafficcard drivers and made a system scan
(sfc /scannow)

Anyone that might know how to handle this problem?
Really frustrating to die/almost die all the time in the game coz of random shut downs...

Thx for all the future help!

btw how to attach the log file? :O it only says a security token was missing so I cant upload it?