Do you need a monitor with this build? Please post the model of your case if it's possible.
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CPU:
Intel Pentium G3258 € 72,90
Motherboard:
MSI H81M-P3 € 43,90
RAM:
Kingston HyperX Savage - DDR3 € 37,90
GPU:
MSI N750Ti 2GD5/OCV1 € 117,90
PSU:
Corsair Builder Series CX430 € 48,90
SSD:
OCZ Trion 150 120GB € 52,90
Total: € 374.4
This is the cheapest I could fit on Intel. Notice the lack of HDD, you should consider if that works for you. There are no cheap storage options at Azerty, so if 120GB isnt enough your best bet would be getting 240GB SSD (same one or Crucial BX200, this one is slightly better imo). I'm not good at AMD builds, I'm pretty sure you can build cheaper on AMD, but the performance will suffer.