On the specs of every R9 290 card i see it says that a minimum of a 750w power supply is "required" however i have yet to see a test of a full system that pulled more than 550W (however less than 500 is typical) of power from the WALL given that power is lost to heat that puts the output of the power supply at less than 500 watts. Also in a recent article Toms managed to get by with a 650w power supply with a 650W power supply! How accurate are these readings from reviewers: anandtech, Tom's, legitreviews, and what is up with the high power "requirement" of these graphics cards?
I'm looking to upgrade my system with a high-end graphics card and i have the Phenom2 955 cpu, a 600w thermaltake Tr2 power supply, a single HDD, and an optical drive. i also have 7 fans in my case. would a R9 290 be asking too much?
Some older PSU (like mine) has lower 12v wattage than it's rating..
mine 750w rating has actual 12v power 650w..
They need to consider this and if the case use lot of HDD/fans/light (or like mine using pump), so they go conservative and list it 750w PSU requirement.. (also they need to consider the aging PSU with caused it to drop power in years of usage)
for your second question, u can use some web PSU calculator on/offered by some PSU maker/brand (the one i use is on enermax website, but there lots of other)
the thermaltake calculator said i should be okay. it just seems silly that the minimum requirement for one 290 is 100w more than the power usage of a sli 770 setup with an overclocked i5. 500 bucks is probably the max on my budget for a single card solution and i just would kick myself for getting the 780 knowing how much better the 290 is.