can i add r290x nr. 5 (or even 6) to my rig?

[loreannl]

Hi,

i have the following hardware:

Coolermaster HAF BX case
- 4x R9 290X with powered risers
- AMD Athlon II X2 3.5 ghz cpu
- ASRock 970 extreme 4 motherboard
- 4x 2GB DDR3 1333mhz memory
- 250GB Harddrive
- 2x 1000 Watt power supply
- Samsung DVD Brander
- 4 big fans
- Windows 7  64bit Home Premium

running stable at 3.9/4.2 Mhz with cgminer 3.7.0 and cgwatcher

I would like to know if i could add another r290x or maybe even two extra cards. Is this possible with my current setup?

Thanks in advance!