Yesterday, my new GTX 970 arrived. I was hella excited, connected it, started up my computer, and... everything was crazy sluggish. Like, it took several minutes to start Minecraft sluggish. "No big," I thought. "I'll restart it and see if the problem persists." So I shut down and it wouldn't even start back up again. Since I'm not completely unsavvy, my immediate first thought was that something was wrong with my power supply. So I did the easiest thing I could think of: I swapped the 6 and the 6+2 cables around on the GPU, as shown in this (exceptionally ugly, but hopefully clear) illustration: I didn't expect it to work, but it was the least amount of effort, so I figured why not. And then the unthinkable happened: It actually worked. So even though my problem is, for all intents and purposes, solved, I'm still genuinely baffled by this. I tried something stupid on a whim. Why the hell would this actually make a difference? Shouldn't these two configurations be functionally identical?
I'm not an electrical engineer by any means, but there's at least a few possibilities I can think of, in no particular order: First, maybe the 2-pin section on that wire (that's now disconnected) wasn't producing enough voltage. Second, maybe it just so happened that one of the connectors wasn't plugged in all the way, which was fixed when you switched them. Or perhaps you inadvertently connected something elsewhere that fixed the problem. And finally, maybe the heat conditions changed, or a wire was blocking the GPU fan that you moved out of the way when you made the swap.
Maybe you just did not have them plugged in properly in the first place. You thought you had, but they weren't.
Among all these answers, what I'm not seeing is some unexpected difference in 6v wires, which means I'm not missing some vital piece of computer knowledge that I wasn't even aware of. Good to know; I actually prefer these sorts of user error, because they're so easily correctible.
I could absolutely see one connector getting just slightly not enough power compared to another, especially with mid-range or lower power supplies. What PSU model are you using? You might want to have a look at one of the many PSU wattage calculators out there on the internet, get a ballpark figure of how much your hardware is potentially using.
It's definitely not the PSU itself being weak (unless it's gotten weaker over age?). This thing is is a 650W PSU, and the calculators have all put me under 500W needed. Further, if that were the case, swapping around connectors almost certainly wouldn't have fixed it.
Sounds like to me that one of the cords simply wasn't supplying enough power. Was it daisy-chained into other components?
I'd have to double check, but I can't imagine that'd make a difference since I'm using the exact same two cords, just plugged into different slots on the GPU. Unless it's because one had a little more power for the +2, which would make sense.
