Dúvida entre placas de video até R$500

Olá amigos estou querendo comprar um placa de vídeo por até R$500. Andei pesquisando na net e encontrei as seguintes placas de vídeo:

Microstar - MSI N550GTX-Ti-M2D1GD5/OC GeForce GTX550 Ti 1GB GDDR5 R$499,89
Core Clock Speed(MHz): 950 MHz
Memory Clock: 4300 MHz
Memory Interface: 192-bit
Bus: PCI-Express 2.0 x16
RAMDAC: 400 MHz, Max. Resolution: 2560 x 1600
Connectors: Dual DVI; Mini HDMI

Powercolor AX5830 1GBD5-PPDH Radeon HD5830 1GB DDR5 R$489,99
Engine Clock: 825 MHz
Memory Clock: 4.2 GHz
Memory Interface: 256-bit
Bus: PCI-Express 2.1 x16
Stream Processing: 1120
Max. Resolution: 2560 x 1600
Connectors: DVI; HDMI; DisplayPort

ECS Elitegroup NGTX550TI-1GPLI-F GeForce GTX 550 Ti 1GB GDDR5 (Fermi) GDDR5 PCI Express 2.0 x16 R$410,00
HDCP Ready SLI Support Video Card
Core Clock: 900MHz
Stream Processors: 192 Processor Cores
Effective Memory Clock: 4100MHz
DirectX: DirectX 11
OpenGL: OpenGL 4.1
HDMI: 1 x mini HDMI
DVI: 2 x DVI

Sapphiretech HD5830 Xtreme 1GB GDDR5 ATI Radeon HD5830 1GB DDR5 R$495,00
Core Clock: 800 MHz
Memory Clock: 4000 MHz
Memory Interface: 256-bit
Bus: PCI-Express 2.1 x16
Stream Processing Units: 1120
Suporta Crossfire. 1x Dual-Link DVI
1x HDMI
1x Mini-DisplayPort

EVGA 01G-P3-1557-KR GeForce GTX 550 Ti (Fermi) 1GB 192-bit GDDR5 PCI Express 2.0 R$403,00
x16 HDCP Ready SLI Support Video Card
Core Clock: 981 Mhz (vs. 952 Mhz Reference)
Shader Clock: 1962 Mhz (v.s. 1903 Mhz Reference)
Stream Processors: 192 Processor Cores
RAMDAC: 400 MHz
Max Resolution: 2560 x 1600
1x mini HDMI, 2x DVI

EVGA 01G-P3-1556-KR GeForce GTX550 Ti 1GB DDR5, R$407,00
Engine Clock: 951 MHz,
Memory Clock: 4356 MHz,
Memory Interface: 192-bit,
Bus: PCI-Express 2.0 x16,
RAMDAC: 400 MHz,
Steam Processor: 192,
Memory Bandwidth: 104.5 GB/s,
Max. Resolution: 2560 x 1600,
Connectors: Dual DVI; Mini HDMI

Asus ENGTX550 TI DC/DI/1GD5 GeForce GTX550 Ti 1GB DDR5, R$480,00
Engine Clock: 910 MHz,
Memory Clock: 4104 MHz(1026MHz GDDR5),
Memory Interface: 192-bit,
Bus: PCI-Express 2.0 x16,
RAMDAC: 400 MHz,
Stream Processors: 192,
Max. Resolution: 2560 x 1600,
Connectors: VGA; DVI; HDMI

HIS H679QN1G2M AMD Radeon HD6790 1GB DDR5 - Cooler IceQ X, R$449,00
Core Clock: 840 MHz,
Memory Clock: 4200 MHz,
Memory Interface: 256-bit,
Bus: PCI-Express 2.1 x16,
RAMDAC: 400 MHz,
Stream Processors: 800,
Max. Resolution: 2560x1600,
Connectors: Upper Single-link DVI

Powercolor AX6790 1GBD5-DH Radeon HD6790 1GB GDDR5, R$465,00
Engine Clock 840MHz,
Memory Clock 1050MHz (4.2Gbps),
Memory Interface 256bit,
DirectX Support 11,
Bus Standard PCIE 2.1,
Display Connectors DL-DVI-I/HDMI/mini DisplayPort

Microstar - MSI N550GTX-Ti Cyclone II GeForce GTX 550 1GB GDDR5 192bits, R$449,00
core clock speed (Mhz): 950,
memory clock speed (Mhz): 4300,
2x DVI, 1x Mini HDMI,
PCI Express x16 2.0

ECS Elitegroup NBGTS450-1GPI-F NVIDIA GeForce GTS 450 GPU 1GB GDDR5 PCI Express 2.0 R$399,00
x16 HDCP Ready SLI Support Video Card,
Core Clock: 850MHz,
Stream Processors: 192 Processor Cores,
Effective Memory Clock: 4000MHz,
DirectX: DirectX 11,
OpenGL: OpenGL 3.2,
HDMI: 1 x mini HDMI, DVI: 2 x DVI

Zotac ZT-50401-10L GeForce GTX550 Ti 1GB DDR5, R$404,00
Engine Clock: 900 MHz,
Memory Clock: 4100 MHz,
Memory Interface: 192-bit,
Bus: PCI-Express 2.0 x16,
RAMDAC: 400 MHz,
Stream Processors: 192,
Max. Resolution: 2560 x 1600,
Connectors: Dual DVI; HDMI; Displayport

Aki segue o link de cada uma delas:

Zotac Geforce GTX550 TI
Asus ENGTX550 TI DC/DI/1GD5
MSI N550GTX - TI Cyclone II 1GD5/OC
ECS NBGTS450-1GPI-F
ECS NGTX550TI-1GPLI-F
MIS N550GTX-Ti-M2D1GD5/OC
PowerColor PCS+ HD5830 1GB GDDR5
Sapphire HD5830 Xtreme 1GB GDDR5
EVGA GeForce GTX 550 Ti Superclocked
EVGA GeForce GTX 550 Ti FPB
HIS 6790 IceQ X 1GB GDDR5
PowerColor HD6790 1GB GDDD5
EVGA GeForce GTX 550 Ti FPB

Eu gostaria de saber qual dessas é a melhor e se vcs tem alguma sugestão.

Obrigado

Abç

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