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Power On to MB at all times

By Savage1701
Jun 13, 2008
  1. I am trying to use just an older socket 370 MB for the PCI slots to hold Gigabyte i-RAM cards. Now, the cards are only supposed to need 3.3 or 5 v power from the PCI bus. They are not supposed to need any data from the MB, cpu, PCI bus, etc.

    I have a couple of these running in an old Socket 370 computer that I just boot to a DOS floppy, as well as on an older Socket 775 system. The cards work fine as RAM disks. Figuring this was fine, I picked up another Socket 370 MB without CPU, Memory, Hard Drive, Video Card, etc. I installed an i-RAM card, and plugged the ATX connector in. I shorted the green line on the ATX connector to one of the grounds. The board lights up, fans run off of it, and the i-RAM card shows it is charging and functional, but the other computer I plug the SATA cable into from the i-RAM drive won't see the drive. I know it's not the card, because I swapped it in and out of the other full socket 370 computer and it worked. I had a similar problem trying to run these cards on a PCI passive backplane with power on. Question is this - when I turn on a full-fledged computer, does it route power or activate chipsets, etc. that just shorting the PSU does not? What I can't figure out is that the i-RAM is drawing normal power according to its indicators. Obviously with no CPU or RAM the MB is "dumb", but that is what I wanted - just a collection of powered PCI slots. Any thoughts are appreciated.
  2. Tmagic650

    Tmagic650 TS Ambassador Posts: 17,244   +234

    I imagine the the iRAM needs motherboard timing pulses, therefore you will need a fully functioning motherboard to host the iRAM
  3. Savage1701

    Savage1701 TS Enthusiast Topic Starter Posts: 153

    Got it !

    Actually, they don't. But, apparently, one of two things was happening: Either the 5-volt line was bad on my PS, although I have not had a problem with it before, OR, the PS was not delivering 5 volts to the MB since nothing was requesting it. I swapped PS's, attached an old SATA hard drive and an old CD-ROM to the PS, and now the i-RAM works fine in the dummy motherboard. I think that was really the only problem - it was not getting a 5-volt signal. Thanks for the suggestions.
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