What would happen if 5970 exceeds 300W?

System instability in general I guess. I've never experienced it but that would be my guess. I doubt it would do any real damage

The unstoppable force meets the immovable object?

Why would the 5890 exceed 300W? The 5970 doesn't, and the 5890 (if it gets made) would be a single GPU.

On a more general note, if any GPU exceeds 300W, nothing special happens as long as your PSU can handle it. It won't suddenly cause any system problems.

the motherboard can only give out a set ammount of power, and the rest is provided by the power connectors to the card - overloads are protected by the psu (cuts out) etc

I want what ur smoking,it has been made and is a dual GPU.

Thats why they lowered the clocks,to keep it under 300W.overclocked it will go over,you just need a good PSU for it is all.

The 5890 has not come out smart a*s... He's talking about a tweaked 5870 much like the 4890 was a tweaked 4870.

And no, i do not think that any single GPU will exceed 300w

the only reason for a GPU to exceed 300 watts would be if it was heavily overclocked and the limiters bypassed on the PCB.
that being said if ATI decides to make a 5990 (5890 is going to be a high binned 5870) it would end up being something like a pair of 5870 chips and they would need to have 2x 8pin or 3x 6pin power and a massive cooler. but that is just speculation from seeing what their past cards are

now if you were talking about a 4890 exceeding 300watts which is possible with a heavy overclock and LN2 cooling you would have to bypass the limiters and have thicker gauge cabling to the power connectors, have a single +12V rail PSU running ONLY the card. all that happens is the entire PCB heats up significantly and the chances for arcing, melting connectors and massive artifacts start to form on the display.

look into the japan overclocking competition that used GTX260's

duh on the title he says 5970 and then in the message itself 5890....

Id like all of you to look at your psu specs.
Then look at the PCI specs.
Then look at ATIs wanting people to oc this card, which is already at 294 or thereabouts.
PSUs say things like up to.
It will/does go over 300 watts.
But, it also has to be PCI compliant, so, at stock, it comes right under it.
A 5890 would only have either better cores and better electronics,caps etc for an even higher oc

I think AMD would have managed to create "cold fusion", but at the cost of the HD 5970's destruction.

Nothing really. There is nothing magical about the 300W limit, it is just the spec that was chosen just to keep things, well, consistent. When any spec is made, there is a factor of safety in it so you are not constantly running at the verge of failure. So 300W is fine, possibly up to 400W is fine, but if you start putting much more than that through the board/cables you are asking for problems.

I was responding to the OP. I didn't notice that the title said 5970 (which does exist, and can indeed go over 300W).

If any GPU exceeds 300W, as I said above, nothing special happens. As long as you have a good PSU, everything keeps working, exactly as it had before.

Also, keep in mind the conductors/wires on a power supply have a certain amperage rating. For example, a 14Ga Cu conductor has an amperage rating of 15A, 18Ga is 10A. I'm not exactly certain what size conductor is used in PSUs, but take each conductor, find the size, the amperage rating and multiply that by the voltage through that conductor. This will give you the maximum wattage that can be safely supplied through the wire while still being under the current rating. That should give you a better idea on the theoretical limit in which the GPU can draw without causing larger problems.

Whoops sorry for mistype in post, i meant 5970. So even though supposedly the board and pci-e 6pin are at 75w at 8 pin is at 150w it'll just go over? Would this be bad for the PSU because it's providing more power to those connectors than it's supposed to? O_o. Would it theoretically be bad for the gpu to have an extremely overclocked 5970? I'm not planning on buying one or anything, just was wondering lol.

Quality PSU = Designed beyond spec, so it's all good / Poor PSU = Massive singularity that engulfs us all.... errr.... some instability and potential fire hazard... and maybe a singularity... or Gremlins!

anandtech seemed to have trouble with overclocking 5970 with a corsair psu...aren't they supposed to be good? O_o

It's not the PSU being capped at 300W, they were able to go well beyond stock, but overclocks are only so stable and it's not about just the PSU.

Someone says why would a 5970 exceed 300 watts, maybe because it does over 300 watts when overclocked. By the way when the 5970 get's too hot it throttles like cpu's do to cool down.
http://www.anandtech.com/video/showdoc.aspx?i=3679&p=16

notice the total system power of 642 watts when oc'ed with a single 5970.
and when you have 2 of them in your comp, they will be throttling more because of heat rising from the bottom card into the top.

theoretically it can surpass 300 watts on closer inspection of the 5970 pcb power connections you will notice that right next to the 6 pin power connector is space for another +2 pin plug wich means ati could produce a card needing 2 8pins, 150+150+75=375 watts