Computer really slow after installing new graphics card.

[Chaotictankvt]

I recently bought a new GeForce GTX 750Ti, I put it in, installed new DirectX, installed Drivers for it, and I noticed a slight decrease in performance, but not much. Could run games at 50 FPS and I played rust for a solid 7 hours. I get off my computer, get on later and no programs will load up, window keeps crashing, and things won't download in steam. Tried uninstalling old drivers, tried using old graphics card. I'm stumped. Please help

My specs are (Exactly as written in Piriform Speccy):

OS: Windows 7 Professional 64-bit SP1

CPU: Intel Core 2 Duo E8500 3.16GHz

RAM: 8GB Dual Channel DDR3 @ 531 MHz (7-7-7-20)

Motherboard: Dell Inc 0200DY (CPU)

Graphics: Nvidia GeForce GTX 750 Ti

Storage: 149 GB Seagate ST316031 ST3160318AS SCSI Disk Device (SATA)
14 GB Kingston DataTraveler

Optical Drives: PLSS DVD+-RW DH-16AAS SCSI CdRom Device

Audio: SoundMAX Integrated Digital High Definition Audio.

 

[Calvin7]

Dell Inc 0200DY is in a OptiPlex 780 which has a 225 watt power supply. That video card needs 300 watt Minimum power supply.

 

[rcald2000]

Download and run HWMonitor. Then play games and check CPU temps. I'm wondering if your CPU is thermal throttling. Give it a shot right now; it should take you 20 minutes tops.

 

[Chaotictankvt]

Dell Inc 0200DY is in a OptiPlex 780 which has a 225 watt power supply. That video card needs 300 watt Minimum power supply.

Or what happens?