PCI-E power connector query

cortexodus

cortexodus

[H]ard|Gawd
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Feb 20, 2009
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I have this PSU

and I have this GPU on its way to me.

The card will require two PCI-E links.

The PSU is semi-modular and has a somewhat unusual (to me, anyways) PCI-E cable in that two 6+2-pin heads are attached in series to a single cable coming from the non-modular set of cables. There is also room for an additional PCI-E power link to the modular ports.

Is that dual-head-on-a-single-cable thing peachy for the GPU I linked to? Seems like too much draw might cause the cable to cook. Should I use one head on it plus the modular PCI-E link?

*EDIT 7-24-2014 - I've had the above card and PSU linked up with the dual-head PCI-E power connector for a couple weeks now without issue :)
 
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Well, the practical in me says you should be fine.
The paranoid in me says to use the separate cable, just in case.

Personally i'd listen to the paranoid side.
 
It may work fine with them daisy chained, but I prefer to run each connector on individual lines. Just seems more safe to have the load coming from 2 sets of cables. Just my opinion though.
 
The PSU has a single 12v rail that does >50 amps.

Having two separate wires would be completely pointless since they'd be fed from a common source anyway.
 
I guess I can't imagine that XFX would put 2x 6+2 heads on one strand if it wasn't supposed to be able to handle it. I will probably go ahead and use the daisy-chained heads first and see if notice any heat build-up on that cable bunch under load.

This is the first PSU I've had with daisy-chained PCI-E heads so I'm just a bit wary of that configuration. Thanks for the input, folks! :)
 
flopticalcube said:
That would depend on the gauge and length of the wire.
Click to expand...

The cable bundle the leads are attached to do seem pretty stout. I'm not sure of the gauge but did note that it felt like that bundle's wires were a slightly larger diameter than typical. I will compare more closely this evening...

Now I just gotta find my calipers :p

Based on this review, it would appear the wires are all 18 gauge.
 
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The standard PCI-E cables run 3 +12V lines that can handle up to 4.17 amps of current. If XFX went out of spec in order to offer two PCI-E taps on a single run of cable, there is no telling how much current it is designed to handle. Of course it could simply be possible that the threaded cable coming from the PSU actually encases the amount of lines needed for two.
 
I think on that gpu...you be ok...a 290x is a different story and a heck of lot more power draw....I personally think you be fine...with that gpu...regarding the wire size i think its no problem...I be surprised if they heat up under load;)
 
i ran crossfired hd7850 2gb with a 3.6ghz x6 1155t off a corsair hx620 with those 6/8 pin pci-e power connectors for over a year without issue. on one card and a 4770k you're not even close to straining that psu to really matter.

P1010036.jpg
 
I know my seasonic unit is made like this.

Has 2 - 6+2 pin connectors on each pci-e cable. Its a problem with the higher end gpus more on that in a bit. It works just fine for smaller cards. Anything that draws less power than a AMD 7970 will be fine. ( ran 7950 crossfire for while with the same power supply with out issue)

Here is what happens when you put a high draw card on a single cable such as my R9-290X (under water and overclocked). The unit was accepted by RMA no questioned asked. I am using two cables now to split the power draw between two sets of cables vs one. It wasn't a instant meltdown problem my computer worked fine for 3-4 months with just a single cable. I suspect the current draw got to high for the wire to handle and heated up causing the connector to melt and short.



Entirely up to you what you do.
 
cortexodus said:
The cable bundle the leads are attached to do seem pretty stout. I'm not sure of the gauge but did note that it felt like that bundle's wires were a slightly larger diameter than typical. I will compare more closely this evening...

Now I just gotta find my calipers :p

Based on this review, it would appear the wires are all 18 gauge.
Click to expand...

Around 2mm should be 14awg. 1.5mm would probably be 18awg. To carry twice the current with the same voltage drop the wire should be 14awg.
 
All this information is good to know...but that card he's ordering i think only pulls like 170 watts....he can run furmark and for an hour and just feel the wire and connector in he's hand....if its not even warm i cant see him having a problem;) at least thats what i would do
You people who tried this with a 290x should have known better...that card draws more than double the power...of course it would burn up...i be willing to bet the wire was hot every time it was used...The op also states its a wire thats non modular....so if it has a problem it should be near the connector on his card or his wire
 
kumquat said:
The PSU has a single 12v rail that does >50 amps.

Having two separate wires would be completely pointless since they'd be fed from a common source anyway.
Click to expand...

ummmmm, no

it is quite possible to exceed the current capacity of the wiring, many threads of melted harness if you look.

This post is fail
 
jojo69 said:
it is quite possible to exceed the current capacity of the wiring, many threads of melted harness if you look.
Click to expand...

I didn't really address kumquat's post for that reason. However, I do understand how he arrived at that incorrect conclusion and I'm ashamed to say that I've experienced a little melt of my own when I was foolish enough to run my old FX-8120 + 990FXA rig with only a single 4-pin 12V CPU connection for a little while :eek:

I didn't realize my mistake until the system would insta-power-down periodically under load. I was fortunate to not cause any damage to anything but a slight melty-ness on the 12v extension cable I was using at the time.

That mistake is a good bit of why I posted this topic. I don't think the daisy-chain link will be an issue for an r9-270x (particularly since it'll be run at OOB clocks) but I certainly wouldn't trust it for something like my 780 HOF, for instance. Thanks again for the input everyone :D
 
I have the 750W version of that psu and had some OC'ed 670 in sli where I had no choice to use one cable per card and it was fine.
Didn't like the idea too much at first but no problem since day one.

Now I use only one cable for my 780 ti OC'ed at 1275mhz and everything is fine the cable doesn't even get hot, got the card ~6 months ago.
 
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