Originally Posted by Imglidinhere
It's not powerful enough to handle two 470s. That's 430w estimated TDP just for the GPUs. I'd upgrade to the TX750 at least.
The TX650 has a +12V wattage capacity of 636W, and the maximum amount of power that a single GTX 470 can pull at stock is approximately 215W. However, 2nd GTX 470 in SLI cannot pull 215W due to scaling - even in the most graphically stressful/demanding conditions. At the most, the two cards together under the highest loads would pull ~350W, maybe
375W - and I am being generous.
So let's go with a combined total of an absolute maximum of 375W between both cards. If this is the maximum possible power draw (and I still believe I'm being generous), then this leaves 261W on the +12V which means that this is what's left for everything that is using the +12V as its power source (most of the system, including the CPU). So this even leaves enough power left over for folding on both the CPU and the two GTX 470s simultaneously.
Let's be even more generous (unrealistic, actually) and say that the maximum power draw is 400W between both cards. This scenario would leave 236W on the TX650's +12V which is still enough power left over.
The Hardware Canucks performed a power consumption test by measuring the power draw at the wall
during a very intense 30-minute graphics test. The result was that their entire computer system caused the power supply to draw 541W from the wall outlet. So now if we say that their power supply was 80% efficient during this power draw, then we can say that the entire computer system was pulling 432.8W during this load. While idling for 30 minutes, their system peaked at 220W. Here is their test system:
Here's the load test:
Here's an image:
Again, this is for the entire system's power draw measured at the wall, and not just the graphics cards. In other words, these figures are what the power supply was pulling from the wall outlet. However, this doesn't mean that 541 is subtracted from the TX650's 650W rating, but instead this is figured out by multiplying these figures by the efficiency as a percentage (e.g. 541 x 0.80 for 80% efficient). So again, 541W at the wall could mean 432.8W if the PSU were 80% efficient during the load. However, even if it were 85% efficient, then that's still only 459.85W.
So I am very confident that the TX650 would have no problem powering an average system that has two GTX 470s in it.
Now, I suppose someone might ask me why I have the HX650 powering my little system with a single GTX 470 in it. The answer is that I originally wanted the HX450, but the cost of international shipping would have made it cost more than what the HX650 was going for at the time.