AMD: Speculation, Rumors, and Discussion (Archive)

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I like PCIe aux power cables. They're efficient; routing all power to a several-hundred-watt GPU through the mobo will not be as efficient even if voltage is raised significantly - 24V or even more. Also, ATX power cable's enough of a bitch as it is, now we'll need an even thicker bundle, or perhaps more likely, two bundles. Thick cables are oftentimes hard to dis/connect to the mobo, and makes futzing around inside a PC bothersome.
 
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Actually with the current spec being quite vague about power (it says in there that 300W products are supported - but fails to mention that cables are required for this), as well as the PCI-SIG's president's statements when speaking to heise about RX 480 ("high power cards are niche"), I am inclined to believe that 300-400-500 Watt via the slot alone might be a misunderstanding or overinterpretation.

Or is there a dedicated slide telling that it's fact? Haven't seen one neither at THG nor Kitguru.
 
I like PCIe aux power cables. They're efficient; routing all power to a several-hundred-watt GPU through the mobo will not be as efficient even if voltage is raised significantly - 24V or even more. Also, ATX power cable's enough of a bitch as it is, now we'll need an even thicker bundle, or perhaps more likely, two bundles. Thick cables are oftentimes hard to dis/connect to the mobo, and makes futzing around inside a PC bothersome.

Yeah I would be concerned trying to squeeze another moderate size connector on an already tight motherboard, my preference would be the aux power cables.
How this affects the existing motherboard ATX power connector will be interesting, because it sounds like the PCIE connectors will no longer be powered through this, well would be a nightmare as this would also need re-designing and spec change if they remained using the ATX 24-pin connector.
And one benefit of the auxiliary, what about SLI/Crossfire as 300W shared back to the PCIe new motherboard connector would not be enough, one also loses flexibility on voltage rail-modularity options associated with good PSU.
They mention it could go up to 500W, but sounds like the current situation where there is the standard and HCS/HCS+, most IHV only implement standard.
Now that is assuming that while each slot support say 300W, this needs to be shared to a single voltage point connector (replacing or more likely separate to the current ATX 24-pin connector) on the motherboard that will probably be the same spec.

Edit:
NVM My mistake looks like there are many connectors now on the motherboard rather than the cards.
Not sure how this is better than the existing auxiliary setup.
If you look closely, there is a single 20-pin power connector like any other modern motherboard.
There are also four 8-pin and two 6-pin power connectors. AMD marked the PCIe power connectors as follows:

P0 ABCD PWR
P1 ABCD PWR
P0 EFGH PWR
P1 EFGH PWR
Cheers
 
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Actually with the current spec being quite vague about power (it says in there that 300W products are supported - but fails to mention that cables are required for this), as well as the PCI-SIG's president's statements when speaking to heise about RX 480 ("high power cards are niche"), I am inclined to believe that 300-400-500 Watt via the slot alone might be a misunderstanding or overinterpretation.

Or is there a dedicated slide telling that it's fact? Haven't seen one neither at THG nor Kitguru.

The standard of power have not been decided yet, thats why its vague. Diferent vendors have diferent opinions from 300 to 500.
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But in the end doesn't really matter, 300W is enough to supply a Titan X...So the number of GPUs with External connectors will be very limited. It will also make GPU and specially custom coolers much simpler to design and allow for better designs as well. Also will help users with low end and small cases.

This will make the building a PC better is every way.
 
I don't see much point for desktop cards. If you connect the cables to the motherboard or the graphic card doesn't really change much.
I guess it is helpful for compute cards though, with easier card swapping and all.
 
I don't see much point for desktop cards. If you connect the cables to the motherboard or the graphic card doesn't really change much.
I guess it is helpful for compute cards though, with easier card swapping and all.
Many of us are using servers these days with 8 or even 16 GPUs in a box. The power cable routing can be quite an issue. Tesla cards put the power connectors on the back of the card, which is much better than putting them on the top. If it's true we can get rid of those cables altogether, that will make server design and maintenance much easier for dense GPU servers.
 
Many of us are using servers these days with 8 or even 16 GPUs in a box. The power cable routing can be quite an issue. Tesla cards put the power connectors on the back of the card, which is much better than putting them on the top. If it's true we can get rid of those cables altogether, that will make server design and maintenance much easier for dense GPU servers.
But the PCIe is sharing a single power connector, in a standard PC that would be the 24-pin ATX, which is specified as either standard/HCS/HCS+, anyway the ATX spec for the 24-pin connector is not enough even to support a single card fully so this needs to be a redesign/spec or more likely an extra molex connector on the motherboard.

However the problem just like now each of those PCIE slots must share the current/voltage from a single point in the new concept, that new connector replacing the existing ATX will need to support X number of slots, meaning it will require at least 600W-800W spec and with the associated Amps current just for that motherboard connector to PSU with a single cable-connector; putting strain on a specific voltage rail and requiring some hefty circuit/tracing as this is no longer distributed with individual auxiliary power design.
The more cards you add, the greater that number becomes and logistically it becomes a nightmare from a motherboard-PSU perspective.
Just 2 cards that use 2x8-pin power connectors each meaning a total of 4 individual power connections between the GPUs and critically the PSU would now be replaced with just 1 cable and 1 connection to the PSU.
Edit:
NVM My mistake looks like there are many connectors now on the motherboard rather than the cards.
Not sure how this is better than the existing auxiliary setup.
If you look closely, there is a single 20-pin power connector like any other modern motherboard.
There are also four 8-pin and two 6-pin power connectors. AMD marked the PCIe power connectors as follows:

P0 ABCD PWR
P1 ABCD PWR
P0 EFGH PWR
P1 EFGH PWR
Cheers
 
Last edited:
Yeah I would be concerned trying to squeeze another moderate size connector on an already tight motherboard, my preference would be the aux power cables.

The motherboard is generally the largest PCB, and with pretty much all modern CPUs having north and southbridge functionalities it also has a lot of empty space to conform with the several ATX/ITX size specs.

Why someone would prefer several dangling cables across the case interior to reach the graphics card(s) instead of everything neatly plugged into a corner of the same large PCB is a bit beyond my comprehension. I'm pretty sure that for quite some years all PCIe 4.0 graphics will still bring the dedicated power connectors for backwards-compatibility (otherwise the product would be DOA) so having that option is a good thing nonetheless.
 
The motherboard is generally the largest PCB, and with pretty much all modern CPUs having north and southbridge functionalities it also has a lot of empty space to conform with the several ATX/ITX size specs.

Why someone would prefer several dangling cables across the case interior to reach the graphics card(s) instead of everything neatly plugged into a corner of the same large PCB is a bit beyond my comprehension. I'm pretty sure that for quite some years all PCIe 4.0 graphics will still bring the dedicated power connectors for backwards-compatibility (otherwise the product would be DOA) so having that option is a good thing nonetheless.

I guess you never had issues then re-plugging anything into the motherboard when it is populated such as fan connectors/etc.
And as I said this now needs to be a 600W minimum connector on the motherboard and probably taking up same/just smaller room than the ATX24-pin.

Edit:
NVM My mistake looks like there are many connectors now on the motherboard rather than the cards.
Not sure how this is better than the existing auxiliary setup.
If you look closely, there is a single 20-pin power connector like any other modern motherboard.
There are also four 8-pin and two 6-pin power connectors. AMD marked the PCIe power connectors as follows:

P0 ABCD PWR
P1 ABCD PWR
P0 EFGH PWR
P1 EFGH PWR
Cheers
 
Last edited:
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