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Strange 'Power on' bug with HD4870 + 860W OCZ Power&COOLING ATX.

Discussion in 'AMD / ATI' started by MatTheCat, Mar 17, 2010.

  1. MatTheCat New Member

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    As part of the process of me checking my rig out in preperation for a crossfire configuration, I have been shifting cables, drives etc around in what will soon be a tad cramped PC tower.

    My OCZ 860W Power&Cooling 'SLI READY' Power Supply Unit, has four PCI-e cables. Two of which have additional optional 8-pin add-on (for NVIDIA cards). The other two just have 6pin heads and it is these other two that I have been using to power my gfx card for the past 18 months. However, just by chance, I hooked my gfx card up with the other two (until now unused) connectors. At first, I couldn't get a display on my monitor...but after powering down and powering up again....I got my display and everything was as normal.

    However after being away for weekend...(with PC in boot/trunk of car), I found that once again, I cannot get the display to come up on my PC. The solution was to use the two cables that have been in the gfx card for the last 18 months!

    What the hell is going on here?

    I have not checked the other two cables for voltage supply as I don't have that kind of device....but they have NEVER been used....and also.....the fan on the graphics card spins away (i.e. the card is receving power)

    Is it possible that components paired up with each other just kind of 'get used to one another' in some bizarre way?
  2. MatTheCat New Member

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    And just on the off chance that someone else should stumble across this thread whilst looking for answers to a similar problem.....

    ...after I got the graphics card working again by plugging in it's best mates of the past 18 months (the two 3 * 12V connectors (6-pin)), without turning PSU power off (which I know you always should), I plugged in one of ther other 6-pin connectors (the until now unused ones with 8-pin option), und alles kam in ordnung!

    Very strange....this could explain quite a lot of disputes when people buying 2nd hand PC parts believe they have been ripped off (intentionally) whilst the seller thinks they are just trying to take the piss.
  3. Mussels

    Mussels Moderprator Staff Member

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    its likely you're overloading one of the rails on the PSU, if its a multi rail unit
  4. 95Viper

    95Viper

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    That supply has a single rail 12V@64A/ 70A peak.

    That is a nice PSU. The only reason it would be the PSU is, if, it was defective.


    If it was bouncing around in the truck of your car for the weekend, I would re-seat everything.
    It is always possible you rattled something loose, maybe, even in the PSU itself.
    :)
    Last edited: Mar 17, 2010
  5. MatTheCat New Member

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    I know it is a good PSU and I serioulsy doubt that it is faulty in the slightest. Just to recap....it done this to me even before my entire desktop was 'bouncing' around in the back of my car for the weekend (and even then everything was well foam padded, boxed, and lying on its arse).

    As stated, the solution was for me to plug in the two original 6-pin connectors. For some reason I knew that this would work and then after doing that and without switching the PSU's power off, I could reconnect using the other connectors and the thing worked.

    Although all PCI-e connectors are the same spec, it is as though my GFX card had somehow gotten used to the 6-pin connectors that it had.....I would challange any electrical engineer to figure this one out.

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