Lol, oh the irony...
PCI-E 3.0 spec allows for 75W from the slot, with each 8-pin connector rated for 150W each.
http://en.wikipedia.org/wiki/PCI_Express#Power
If you are going to criticize something at least know what you are doing.
The Spec is 375W from 2 x 8 - pin + 150W from the PCI-e slot for a total of
525W.
The thing that makes me suspect their test is invalid is that if they were truly maxing out the GPU, the clock should have stayed solid at 1018 MHz. Both AnandTech and HardForum reported 1018 MHz on every game they tested (except for a couple that were power throttled). In the video you linked, the GPU frequency bounces around right from the start. Something doesn't seem right.
Lol, oh the irony...
PCI-E 3.0 spec allows for 75W from the slot, with each 8-pin connector rated for 150W each.
http://en.wikipedia.org/wiki/PCI_Express#Power
Damn.
Irony indeed.
I was going of my memory. Which has been proved wrong.
Should have looked it up.
Thanks for the correction.
:thumbsup: It happens...
I'm surprised there isn't a switch that lowers clocks to fit the card within PCI-E spec. Maybe it just wasn't possible, or AMD didn't think it was worth the effort.
The odd thing is that I believe each pin is capable of handling 11A. This means that one single 8-pin PCI-E connector can safely transport 400w at 12v (which is what the 6/8 pin PCI-E connectors supply). So with two connectors rated to handle almost 800w between them, there really shouldn't be any safety concerns.Damn.
Irony indeed.
I was going of my memory. Which has been proved wrong.
Should have looked it up.
Thanks for the correction.
They should have just added a 6 pin or 8 pin.
Would have saved them these criticisms.
Someone mentioned the AT article has an explanation for why they didn't.
I'll read it later.
Have an exam in 3 hours.
Speaking of power delivery, lets talk about the 2 8pin PCIe power sockets that are found at the top right side of the card. For those of our readers who can quote PCIe specifications by heart, the standard limit for an 8pin PCIe socket is 150W, which in this configuration would mean that the R9 295X2 has a 375W (150+150+75) power delivery system. By PCIe standards this has the board coming up short, but as we found out back in 2011 with the launch of the 6990, when it comes to these high end specialty cards PCIe compliance no longer matters. In the case of the 6990 and now the R9 295X2, AMD is essentially designing to the capabilities of the hardware rather than the PCIe specification, and the PCI-SIG for their part is not an enforcement body. Other than likely not being able to get their card validated as PCI-Express compliant and therefore included on the Systems Integrator List, AMD isnt penalized for exceeding the PCIe power delivery standard.
So why does the 500W R9 295X2 only have 2 PCIe power sockets? As it turns out this is an intentional decision by AMD to improve the cards compatibility. Dual dual-GPU (Quadfire) setups are especially popular with boutique builders and their customers, and very few PSUs offer more than 4 8pin PCIe power plugs. As a result, by using just 2 power sockets the R9 295X2 is compatible with a wider range of PSUs when being used in Quadfire setups. Meanwhile on the power delivery side of the equation, most (if not all) of the PSUs that can reliably push the necessary wattage to support one or two R9 295X2s have no problem delivering the roughly 220W per socket that the card requires. Which is why at the end of the day AMD can even do this, because the PSUs in the market today can handle it.
Speaking of power, its worth pointing out that AMDs official system requirements for the R9 295X2 call for a PSU that can deliver 28A per 8pin PCIe power connector, with a combined amperage of 50A. For most PSUs this means youre looking at an 800W PSU being required for a single card, and a 1500W PSU for a Quadfire setup.
Upon finding this we asked AMD why they were using such a relatively low temperature limit, and the response we received is that it’s due to a combination of factors including the operational requirements of the CLLC itself
The odd thing is that according to Molex, each pin is capable of handling 11A. This means that one single 8-pin PCI-E connector is capable of handling 400w at 12v (which is what the 6/8 pin PCI-E connectors supply). So with two connectors rated to handle almost 800w between them, there really shouldn't be any safety concerns.
While the board itself is drawing more power from the connectors than PCI-SIG allows in their standards, it's still not anywhere close to what the connectors themselves are capable of handling.
Trust me, this threw me off also when the first cards went over 300w. I couldn't understand how the cards were PCI-SIG certified when they went over the allowable limits set forth by their own standards. But as it turns out, PCI-SIG doesn't even test for power draw as part of their certification process. Why they would set an upper limit and then not test for it is beyond me. But there it is.
This is from the AT article. Basically the only downside to not following the PCI spec is you cannot be certified as PCI-E compliant. And that boutique builders want to be able to put two cards into one system. If they added another power port, then you would be stuck with a single card as no PSU has more than four 8 pin connectors.
The odd thing is that I believe each pin is capable of handling 11A. This means that one single 8-pin PCI-E connector can safely transport 400w at 12v (which is what the 6/8 pin PCI-E connectors supply). So with two connectors rated to handle almost 800w between them, there really shouldn't be any safety concerns.
While the board itself is drawing more power from the connectors than PCI-SIG allows in their standards, it's still not anywhere close to what the connectors themselves are capable of handling.
Trust me, this threw me off also when the first cards went over 300w. I couldn't understand how the cards were PCI-SIG certified when they went over the allowable limits set forth by their own standards. But as it turns out, PCI-SIG doesn't even test for power draw as part of their certification process. Why they would set an upper limit and then not test for it is beyond me. But there it is.
Between throttle or not trottle, the truth is: 295x2 trottles, yes. But not as often as 290/290x-deafult/290x-uber throttles.
I think the real benefit here is that you can now quad fire 290X without worrying about throttling and PCIe bandwidth. 290X QF is also now an option on 990FX boards.
The odd thing is that I believe each pin is capable of handling 11A. This means that one single 8-pin PCI-E connector can safely transport 400w at 12v (which is what the 6/8 pin PCI-E connectors supply). So with two connectors rated to handle almost 800w between them, there really shouldn't be any safety concerns.
While the board itself is drawing more power from the connectors than PCI-SIG allows in their standards, it's still not anywhere close to what the connectors themselves are capable of handling.
Trust me, this threw me off also when the first cards went over 300w. I couldn't understand how the cards were PCI-SIG certified when they went over the allowable limits set forth by their own standards. But as it turns out, PCI-SIG doesn't even test for power draw as part of their certification process. Why they would set an upper limit and then not test for it is beyond me. But there it is.
TechReport's review is weird. The complete opposite of other reviews. Crossfire didn't seem to work so well for them.
The odd thing is that I believe each pin is capable of handling 11A. This means that one single 8-pin PCI-E connector can safely transport 400w at 12v (which is what the 6/8 pin PCI-E connectors supply). So with two connectors rated to handle almost 800w between them, there really shouldn't be any safety concerns.
While the board itself is drawing more power from the connectors than PCI-SIG allows in their standards, it's still not anywhere close to what the connectors themselves are capable of handling.
Trust me, this threw me off also when the first cards went over 300w. I couldn't understand how the cards were PCI-SIG certified when they went over the allowable limits set forth by their own standards. But as it turns out, PCI-SIG doesn't even test for power draw as part of their certification process. Why they would set an upper limit and then not test for it is beyond me. But there it is.
You still have to worry about PCI-e bandwidth. Most upper end mainstream setups still give only 16x PCI-e and then split that to 2x 8x PCIe for SLI/CF, that would mean each dual GPU card would have only 8x PCIe (4 lanes of banwidth per GPU...). At best this opens up more opportunities to go with more than two GPUs as you would be less limited in your motherboard selection. Not that anyone sane and wanting to go with more than a single R9 295 would compromise their rig with an entry level motherboard (ie you'd be pretty crazy to put more than 1 of these in something less than at least a high end 4770K rig or ideally a s2011 setup)
Found some more great info -
Even though the specification allows for a delivery capability of 75 W (six-pin connector) or 150 W (eight-pin connector), the total power-handling capacity of these connectors is at least 192 and 288 W, respectively, using standard terminals, and even more using the HCS or Plus HCS terminals.
http://www.tomshardware.com/reviews/power-supply-specifications-atx-reference,3061-12.html
A 6-pin PEG has the same amount of 12v leads as an 8-pin peg, but the 6-pin only uses two of them.