Problèmes après changement carte graphique

Bonjour, je possède un SHUTTLE XPC dont voici les composants :
* Chassis
G2-type chassis made of aluminum, silver color
storage bays: 1 x 5.25", 2 x 3.5" (1 internal)
dimensions: 30 x 20 x 18.5 cm (LWH)
weight: 2.85 kg net / 4.65 kg gross
* Mainboard
Shuttle FN41, Shuttle form factor, proprietary design for SN41G2
chipset: NVIDIA nForce2 (Crush 18G)
Award V6.0PG BIOS, 4MBit flash memory
with hardware monitoring and ACPI power management functions
dimensions: 25.4 x 18.5 cm
* Power supply unit
200 Watt mini PSU, supports 115/230V
connectors: 20-pin ATX, 4-pin ATX12V
* Processor support
Socket A supports AMD Athlon XP, Duron and Sempron processors
at 333, 266 oder 200 FSB
supports Burn Proof CPU protection for Athlon XP
* Processor cooling system
Shuttle I.C.E. (Integrated Cooling Engine)
advanced Heatpipe technology
smart fan control, 80mm cooling fan
* Memory support
2 x 184 pin slots, supports Dual Channel
supports PC3200/2700/2100/1600 (DDR400/333/266/200) DDR SDRAM memory
up to a total size of 2GB
Caution: DDR400 is only supported in conjunction with an additional (plugged-in) AGP-graphics card
no support of buffered or ECC-modules
* Expansion slots
1 x AGP 8X/4X (1,5V only)
1 x 32 Bit PCI (v2.2)
* Integrated graphics controller, Dual VGA
Northbridge with integrated GeForce4 MX graphics processor
up to 128MB Shared Memory (UMA)
Highend-256Bit-2D/3D-accelerator
nView Dual-Display-architecture
integrated 300MHz D/A-converter
max. resolution: 1920x1440
including TV output
* 6-channel Audio
Realtek ALC650 5.1 channel audio controller
AC97 v2.2 compiant
analog: line-out (6-ch), microphone, CD-in, AUX
digital: optical SPDIF output
* LAN controller
Realtek 8201BL Fast Ethernet network controller
supports 10 / 100 MBit/s opteration
* Firewire controller
IEEE1394 Firewire controller Realtek 8801
with 3 Firewire connectors (1x front and 2x rear)
supports 400Mb/s, 200Mb/s, 100Mb/s data transfer rate
* Drive connectors
2 x IDE ATA 133 drives
1 x floppy disk drive
* Front-panel I/O
Microphone
Headphone (Line-out)
2x USB 2.0
Firewire (6 pol.)
optical SPDIF output
* Back-panel I/O
2 x VGA monitor connectors
TV out (S-video/composite)
2 x Firewire (6 pin)
PS/2 for mouse and keyboard
LAN (RJ45)
2 x USB 2.0
6-ch Audio line-out (2x rear/front, bass/center)
Serial port (COM)
optional Wireless LAN module
optional parallel port
* Other onboard connectors
2 x USB 2.0 (total 6x)
1 x CDROM input
1 x AUX
1 x Infrared interface
3 x fan connectors
* Conformity
This device is classed as a technical information
equipment (ITE) in class B and is intended for use in
living room and office. The CE-mark approves the
conformity by the EU-guidelines:
- EMV-guideline 89/336/EWG electromagnetic tolerance
- LVD-guideline 73/23/EWG use of electric devices
within certain voltage-limits



J'ais installerune carte graphique SAPPHIRE RADEON HD 3650 512MO AGP

Depuis son installation le lecteur WMP 11 ou VLC ne lise plus les vidéos.
Quand j'ouvre une vidéo il apparait à l'écran un carré vert mais en revanche le son est nikel..

J'ais vérifier dans le poste de travail et l'on me dit que tout est bien installé correctement et que tout fonctionne bien..

Si quelqu'un peut m'aider ce serait super cool !!

D'avance Merci.