GT640M LE 玩DOTA2 過熱 關機

ghostz

顯卡：GT640M LE
Operating System: Windows 8.1 Pro 64-bit (6.3, Build 9600) (9600.winblue_gdr.130913-2141)
           Language: English (Regional Setting: English)
System Manufacturer: LENOVO
       System Model: Lenovo IdeaPad Y480
               BIOS: InsydeH2O Version 03.71.515DCN40WW(V2.07)
          Processor: Intel(R) Core(TM) i7-3610QM CPU @ 2.30GHz (8 CPUs), ~2.3GHz
             Memory: 8192MB RAM
Available OS Memory: 8094MB RAM
          Page File: 2772MB used, 13513MB available
        Windows Dir: C:\Windows
    DirectX Version: DirectX 11
DX Setup Parameters: Not found
   User DPI Setting: Using System DPI
System DPI Setting: 96 DPI (100 percent)
    DWM DPI Scaling: Disabled
     DxDiag Version: 6.03.9600.16384 64bit Unicode

我已經把dota所有特效關閉了
硬盤溫度依然達到56度
而顯卡溫度達到86度

一開始我以為是筆電內灰塵太多，拿去清理後依然如此
究竟怎麼回事？誰能幫我解決