請幫幫忙..電腦換了顯卡後會lag..

前幾日換了顯卡後,電腦跑遊戲開始會lag了(遊戲:Spiral Knights)
一開始以為是驅動沒灌好,但整個重弄後,還是一樣;
後來也有試著把遊戲砍掉從灌,但還是一樣,想請各位大大幫個忙想個辦法..
以下是電腦資訊:
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System Information
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Time of this report: 3/30/2012, 22:01:09
Machine name: YEN-BDF53DE3A5D
Operating System: Windows XP Professional (5.1, Build 2600) Service Pack 3 (2600.xpsp_sp3_gdr.111025-1629)
Language: Chinese (Regional Setting: Chinese)
System Manufacturer: System manufacturer
System Model: P5K SE
BIOS: BIOS Date: 11/30/07 14:01:40 Ver: 08.00.12
Processor: Intel(R) Core(TM)2 Duo CPU E4500 @ 2.20GHz (2 CPUs)
Memory: 2048MB RAM
Page File: 1007MB used, 2932MB available
Windows Dir: C:\WINDOWS
DirectX Version: DirectX 9.0c (4.09.0000.0904)
DX Setup Parameters: Not found
DxDiag Version: 5.03.2600.5512 32bit Unicode

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Display Devices
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Card name: NVIDIA GeForce GT 440
Manufacturer: NVIDIA
Chip type: GeForce GT 440
DAC type: Integrated RAMDAC
Device Key: Enum\PCI\VEN_10DE&DEV_0DE0&SUBSYS_83B01043&REV_A1
Display Memory: 1024.0 MB
Current Mode: 1280 x 800 (32 bit) (60Hz)
Monitor: Monitor Max Res: 1600,1200
Driver Name: nv4_disp.dll
Driver Version: 6.14.0012.6785 (English)
DDI Version: 9 (or higher)
Driver Attributes: Final Retail
Driver Date/Size: 3/28/2011 18:27:30, 6407936 bytes
WHQL Logo'd: Yes
WHQL Date Stamp: n/a
VDD: Mini VDD: nv4_mini.sys
Mini VDD Date: 3/28/2011 18:27:32, 9933952 bytes
Device Identifier: {D7B71E3E-4EA0-11CF-7269-BCA300C2CB35}