Pci-e power cables- how many?

Discussion in 'Videocards - NVIDIA GeForce' started by ratzuk, Mar 8, 2008.

  1. ratzuk

    ratzuk Member

    Messages:
    17
    Likes Received:
    1
    GPU:
    Inno3d 980
    I have got a 8800GTX card with Two power cables connected.

    If i wanted to Sli another GTX how do i get enough power cables ?
    All the adapters i have seen connect 2x molex to 1 Pci-e, does that mean i need 4 spare molex adapters to power this card.

    Thanks
     
  2. Andrés

    Andrés Ancient Guru

    Messages:
    4,555
    Likes Received:
    1
    GPU:
    Sapphire HD 6950 2Gb
    Typically you'll want to replace your PSU with one that comes with native PCIe power connectors, at least two of them. This way you will only need two more adapters to get the four you need. Besides, two 8800GTX need a lot of power and I don't think a 550w PSU can handle it.
     
  3. ---TK---

    ---TK--- Ancient Guru

    Messages:
    22,110
    Likes Received:
    2
    GPU:
    2x 980Ti Gaming 1430/7296
    true that 1 have a 550 watt and i would never sli without upgrading my psu
     
  4. PredatorX64

    PredatorX64 Member

    Messages:
    47
    Likes Received:
    0
    GPU:
    HD4850 + 9600GT Physx
    For 8800GTX you better get one 750W or higher for SLI. Never try it with 550W PSU. You will be upset with the result.

    Start from 750W you will get 4 PCI-X 6pin connector
     

  5. ratzuk

    ratzuk Member

    Messages:
    17
    Likes Received:
    1
    GPU:
    Inno3d 980
    My profile was wrong it isn't a 550 psu

    It is (not much better) a 650w with dual pci-e connectors.
     
  6. ---TK---

    ---TK--- Ancient Guru

    Messages:
    22,110
    Likes Received:
    2
    GPU:
    2x 980Ti Gaming 1430/7296
    you would need the 2 pcie connectors for 1 card and 4 moldex for the other card might work how much equipment do you have in your rig/. pci drives fans etc
     
  7. ratzuk

    ratzuk Member

    Messages:
    17
    Likes Received:
    1
    GPU:
    Inno3d 980
    No other pci cards

    2x Sata HD
    1x Sata DVD

    3x 120mm fans


    Sorry for sounding a bit thick on this subject but i really don't understand why or how a pci-e connector needs power from 2x molex. oh well

    So i need 4 spare molex right, can i split 1 spare molex into 2 then use these 2 to power 1 pci-e connector. then do same again....
    Hope you understand above.
     
  8. ---TK---

    ---TK--- Ancient Guru

    Messages:
    22,110
    Likes Received:
    2
    GPU:
    2x 980Ti Gaming 1430/7296
    you may i say may be able do do that but i dont know. how many amps on the 12v rail do you have dual 12 v rails
     
  9. Makalu

    Makalu Ancient Guru

    Messages:
    4,197
    Likes Received:
    2
    GPU:
    EVGA 8800 Ultra
    A 6-pin PCI-E connector has 3-12V wires and 3-grounds. A 2-molex to 1-PCI-E adapter provides 2-12V and 2-grounds. The PCI-E connector is rated for 9 amps maximum (although it is specified for only 6.5A). Each 12V circuit on a molex connector is rated for 6.5A so they use two of them to cover the safety regulations of the PCI-E connector. One molex would probably suffice...especially in your particular application since the external connectors on the 8800GTX's only pass about 3.5A each...and some PSU's actually only have one of the three PCI-E 12V wires connected but they probably shouldn't do that. If you can't spare 4 molexes then you might be able to use two of these:

    http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=186&products_id=2664

    HOWEVER...if both of your PCI-E connectors are on the same cable then you would be essentially plugging the Y adapter into the same current carrying capability built into your PSU and I don't recommend it. If each of your PCI-E connectors is on a separate cable running back to the PSU then you'll be ok. Performance-pcs is in Florida but they will ship to the UK.
     
  10. PredatorX64

    PredatorX64 Member

    Messages:
    47
    Likes Received:
    0
    GPU:
    HD4850 + 9600GT Physx
    Please remember that usually 4x PCI-X 6pin connector available only in 750Watt PSU or higher. the manufacture have reason for this.

    You can use 650watt PSU to power 8800GTX/ULtra SLI. but you must check you current ampere. because when your VGA Hit Peak Power consumption, you will got problem with your system. Some time your PSU will Broken or Other part will be damage.

    Please be careful with this.
     

Share This Page