GPU-s are really power-hungry. Tech sheets say, that NVIDIA GTX 295 draws 289 Watts under full load. Direct measurement show, that it reality it’s still 200-220 Watts. Three-four of these cards per system, and combined power requirements rise to 1300 – 1500 Watt territory.
Basically there are 2 ways to cope this power need
1. One powerful 1,5 KW PSU with 4 x 6-pin + 4 x 8-pin PCI-E connectors
2. Two 750 Watt PSU-s, both having at least two PCI-E sets.
What are the benefits?
1. Easier to build, doesnt need PSY sync
2. Doesn’t need 2 PSU case
1. Cheaper PSU-s (2 x 750 W price < 1 x 1500 W price
2. Safer, cause of lower currents
Price/performance charts based on ThermalTake ToughPower series
Last chart shows, that power-supplies in 500 – 750 Watt area are considerably cheaper than units from 1000 + area. So, rule of thumb is to use < 1000W units.
- One PSU 1500 W = 330 €
- Two PSU à 750 W = 220 €
Conclusion, one big supply solution is 50% less cost effective than double PSU solution