That PSU is under-rated for even ONE 5970 (pretty sure) ... forget TWO !
This *should* handle TWO 5970s ... Confirm!
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139009&cm_re=corsair-_-17-139-009-_-Product
NOTE: Pretty sure the 5970 uses TWO PCIe 6(+2)-Pin PWR connectors (each). ... This PSU has 4 of them.
Type ATX12V 2.2 / EPS12V 2.91
Maximum Power 850W
Fans 140mm Thermally Controlled
PFC Active
Main Connector 20+4Pin
+12V Rails Single
PCI-Express Connector 4 x 6+2-Pin
SATA Power Connector 8
SLI Ready
CrossFire Ready
Modular No
Efficiency > 80%
Over Voltage Protection Yes
Overload Protection Yes
Input Voltage 100 - 240 V
Input Frequency Range 50/60 Hz
Input Current 12A
Output +3.3V@30A, +5V30A, +12V@70A, -12V@0.8A, +5VSB@3A
MTBF >100,000 Hours
Dimensions 5.9"(W) x 3.4"(H) x 5.9"(L)
Features
Connectors 1 x Main connector (20+4Pin)
1 x 4-Pin/8-Pin EPS Connector
4 x PCI-E
2 x Floppy
8 x Peripheral
8 x SATA Power
Features Guaranteed to deliver rated specifications at 50°C
80%+ energy efficiency at 20%, 50% and 100% load condition for less heat generation and lower energy bill.
Active Power Factor Correction (PFC) with PF value of 0.99.
Dedicated single +12V rail offers maximum compatibility with latest components.
Supports the latest ATX12V v2.2 and EPS12V 2.91 standards and is backwards compatible with ATX12V 2.01 systems.
High quality Japanese capacitors provide uncompromised performance and reliability.
Powerful +5Vsb rail with 3A rating.
Guaranteed compatible with dual-GPU configuration.
Auto switching circuitry provide universal AC input 90~264V.
Over Current/Voltage/Power Protection, Under Voltage Protection, and Short Circuit Protection provide maximum safety for your critical system components
Manufacturer Warranty
Parts 5 years limited
Labor 5 years li