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-   -   2 cables or 1 to power up GPU? (http://www.jonnyguru.com/forums/showthread.php?t=13722)

Makentox 10-14-2016 03:19 PM

2 cables or 1 to power up GPU?
 
https://www.asus.com/Graphics-Cards/...pecifications/
http://www.evga.com/Products/Product...210-GQ-0650-V1
Hello,
Do i have to use 2 pcie cables from PSU to power up GPU or will one cable with 2 connectors do the job?

Tator Tot 10-14-2016 04:26 PM

Dividing the load up between 2 cables is a better solution; but if you really want a clean look to your build, it's fine to use a single cable.

quest for silence 10-15-2016 01:19 AM

Quote:

Originally Posted by Tator Tot (Post 131521)
Dividing the load up between 2 cables is a better solution; but if you really want a clean look to your build, it's fine to use a single cable.

+1

Makentox 10-15-2016 06:50 AM

But how using 2 cables is better? Performance? Stability? Will GPU draw too much of currency and overheat?

quest for silence 10-15-2016 07:55 AM

AFAIK because that reduces cabling resistance, but usually (AFAIK) that's also negligible.

rafal_iB_PL 10-15-2016 04:47 PM

Quote:

Originally Posted by Makentox (Post 131533)
But how using 2 cables is better? Performance? Stability? Will GPU draw too much of currency and overheat?

Current, not currency.

And actually it will draw roughly the same current in both ways. But when you have 2 cables, current splits between them. When on one cable, first PCI-E connector takes combined current for both of them (via Kirchoff's Current Law). This can be problematic if you have power hungry card as it could be more than single connector can handle (connectors are known to burn with 300+ W board power consumption, 250-300 W ones could be problematic longer term). Your 670 is a bit more frugal though, so if you don't OC card heavily, you should be fine.

sdbardwick 10-15-2016 05:35 PM

Quote:

Originally Posted by rafal_iB_PL (Post 131544)
When on one cable, first PCI-E connector takes combined current for both of them (via Kirchoff's Current Law).

So you are saying that no current flows in l2 below?
Code:

12V-------+----------+
          |          |
          | l1      | l2
          |          |
GND-------+----------+


McSteel 10-15-2016 06:01 PM

Quote:

Originally Posted by sdbardwick (Post 131547)
So you are saying that no current flows in l2 below?
Code:

12V-------+----------+
          |          |
          | l1      | l2
          |          |
GND-------+----------+


Indeed it doesn't. But that's not an accurate representation of the circuit that the chained PCI-E cable makes. It's this one:

Code:


12V---------------+
                  |
            +----+----+
          LOAD      LOAD
            +----+----+
                  |
GND---------------+

So the voltage is the same on both attached devices, and the current flow will depend on their internal impedance (which goes down as power requirements go up).

cheapie 10-16-2016 01:58 AM

Quote:

Originally Posted by sdbardwick (Post 131547)
So you are saying that no current flows in l2 below?

I think the concern was more along the lines of this:
Code:

      J1A        J2A
+12V---O----------O
      |          |
      |          |
      \          \
      /CARD      /CARD
      \1        \2
      /          /
      \          \
      |          |
      |          |
GND----O----------O
      J1B        J2B

Since the cables are often constructed by crimping 2 wires into each pin on the first connector (one to the PSU, one to the second connector), all current for the 2 connectors (J1 and J2 here) will be flowing through the pins of the first connector (J1).

Seeing as how that's a crimped connection, I'd assume that the resistance would be even lower than that of the connection to the socket. Therefore, I wouldn't think it would be much of an issue.

Apemantus 08-24-2017 10:10 PM

My first post here. I'm sorry if this is too stupid to ask. I apologize. Does it matter if you use two cables that each have "dedicated" single-ended PCI-E connectors or if you use two cables that each have double-ended PCI-E connectors on the GPU side? I have an ASUS 1080 Ti with two 8-pin power connectors.
If this question is a waste of time, feel free to delete my account and ban me from the Internet forever. I'll go quietly.


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