Re: 35DP35 needs stiff +12 to avoid stuttering startups

Discussion in 'Intel' started by Bob Bailin, Jul 21, 2008.

  1. Bob Bailin

    Bob Bailin Guest

    "Chuck Olson" <> wrote in message
    news:...
    > I've been having a bit of trouble with recurring re-starts on boot-up. It appears as if
    > hard drive spin-up might be pulling down the +12 enough to affect Quad CPU operation.
    > With two 160 GB drives in a mirror raid array, start-up from Stand-by was undependable,
    > with maybe 20 percent of the times interrupted , causing a full re-boot. Then I added a
    > 500 GB third drive and that completely ruined any chance of start-up from Stand-by. Even
    > full boot-up was interrupted with many automatic re-tries as each time the CPU shut down
    > from glitches coming through on the +12.
    >
    > My PSU is a 500 watt Ultra, but the combination of its transient response, the wire
    > resistance in the long run to the 2x2 power connector , and the sensitivity of the CPU
    > regulator to variations on the +12, is just enough to cause serious problems.
    >
    > I decided to modify the wiring that's supplied on this Ultra PSU. There are two
    > connectors furnished for CPU +12 - - a 4x2 with 4 yellow and 4 black wires, and a 2x2
    > with 2 of each color crimped in and extended another 4 inches. The 35DP35 requires the
    > 2x2 connector, so I decided to cut off the 4x2 connector and for each color take all 4
    > wires of one color and solder splice them together with the 2 of that color to the small
    > connector. This reduced the lead resistance to about 1/2 of what the 35DP35 saw before
    > the modification. The result of this change turned out to be improved reliability of
    > boot-up with all three drives running. It didn't get to the point where I can start up
    > from Stand-by with regularity, but a full boot-up is no longer a problem.
    >
    > Maybe in some future version of this board, some provision for delay in spin-up of a
    > third or higher drives can be elected in the BIOS in order to spread out the timing of
    > disturbances in the +12, and of course, more pins in the CPU power connector and heavier
    > wires from the PSU would probably help, too.


    Or, you can buy a known quality PSU that maintains a stable voltage across
    the full range of loads. PC Power & Cooling is one such manufacturer of
    reliable PSU's.

    Bob
    Bob Bailin, Jul 21, 2008
    #1
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