9-series 4 Pin MXM GPU power vs 10-series 6 Pin

Hi all,

I have a p751dm with a 4-pin power connector for the gtx 980 desktop card.

Managed to score a gtx 1080 from MSI (only paid a bit more than a new desktop 1080) that I would like to install. It arrives tomorrow. Unfortunately, it seems that the MSI accepts a 6 pin power connector. I expect that would be a third rail? Can I duplicate one rail? Or would that make my voltages sensitive to oscillations?

If someone knows the power input pinouts here, that would be awesome. I may have to assemble my own regulator to make this all work. I am excited, and any input from you guys would be great.

bob

 

This seems to suggest the Aux power is really just a single rail at 7-20V.

Can anyone confirm? I'd expect it to match up with whatever the battery/PSU voltage sits at.

Does this mean that all the regulators are on the card itself?

With the 10-series version, does this change?

 

I can confirm, I've measured this on a p-870dm-g and it is exactly as the schematics show. I imagine the p751dm would be the same.

When plugged in to AC power, 20v is present on both positive pins on that connector.

As for the 6-pin power, I don't know. Is the esm available for any laptop that has the 6-pin power?

 

Thanks aarpcard!

Any resellers, do you know whether the ESM for 7xxdm2 is kicking around?

The card arrives tomorrow. I'll check the heatsink fit (expecting to need quite a few adjustments), as well as some close-ups of the power distribution.

Hopefully I can just rig up a 4 to 6 pin adapter. We'll see.

 

@bobthedespot check PM

 

PM me the info as well if possible. Going to come in handy when i try to mod a cable to power the Clevo 1080 ( form my DM3) in my DM1 , later this weekend. Would be much appreciated.

 

Looks like an even split 4x4 at supply voltage. Good luck with the mod. I'll let you know how it goes tomorrow. May have to EC mod as well to force boot.

 

Anyone got a guess on the pinout of the 6pin MSI cable?

 

Since there's only two nets, power and ground, eventhough there are six pins, you can just check which pins on the connector are connected to ground by testing continuity to a known ground. And then all the other pins (that aren't connected to ground but to each other) are the power pins.

EDIT: Another tidbit. The circuitry that generated PWR_SRC is essentially identical on the p377sm-a, p870dm, p870dm3, p751, maybe more too. PWR_SRC is the same net that provides power through the MXM connector and to the auxiliary 4 or 6 pin connector. There are no extra phases on the motherboard - contrary to what a lot of people will tell you. (What caused this confusion was the presence of an inductor near the power connector(s) that was actually being used on a different rail.)

The PWR_SRC circuitry on ALL of these laptops is capable of delivering ~280 watts. The only reason the auxiliary 4 or 6 pin power connectors exist is because the MXM connector isn't capable of handling more than 125 watts according to its spec. The extra power connector simply adds a conductive path in parallel and reduces the burden on the MXM connector.

This means you can run the cards without the extra power cable attached (but only do so at non 3d clocks to avoid burning out your mxm slot.) This also means laptops that don't have the extra power port, like the p377sm-a but have similar PWR_SRC circuitry are fully capable of supporting a GTX 1070 or GTX 1080. You would only need to tap into the PWR_SRC rail with a wire and run it to the MXM module so you don't burn your MXM connector.

I obviously want to try play with this lol, but 1070's and 1080's cost money =P

 

Basically load sharing?

 

Wow that's so cool aarpcard. Plus rep.

I'm pretty excited to get the 1080 working in the p750dm. What would really get me stoked is running it in my x7200... I have a world record holding 990x from back in the day. It can still hit 5.0 Ghz on water at all 12 threads. Stable through Firestrike. Would KILL to put this 1080 in that computer... what a beast that would be.

Any idea if I should expect to have to mod the EC on the MSI card to prevent thermal throttling?

As an aside, in the x7200 there is room for a phase change loop.... if I can disable all thermal throttling I know I could make this sucker run cool enough to not worry...

 

One more thing to note is if anyone plans on putting one of these cards in a notebook that doesn't have the auxiliary power connector, don't forget to hook up the ground pins from the auxiliary connector on the mxm module to ground on the motherboard.

The current has to travel back through the grounds in the mxm slot and they have the same rating. . .

 

Also the soldering job needs to be good if you do it that way and from a decent contact area.

 

So I got boot with the 1080 in the x7200. Will keep you guys updated when I get the drivers sorted out. Really exited... might see 16k+ on firestrike.

 

will be nice put one 1080 on DM1