Rodney Pont wrote:
On Thu, 04 Jun 2009 18:05:28 -0500, Ken wrote:

Either you blew something by plugging the ram in while the standby
power was on or the new ram requires more standby power than the power
supply can produce.
This makes the most sense. I am not sure the standby current is listed
for either PS on the label. Each rail is, but not the standby current.

It is on every psu I've looked at, +5Vsb. It's not very high about 1amp
but I did have a motherboard that required 1.5amp minimum.

The power supply comes fully on initially, as another poster explained,
to run the cpu and read the BIOS to see what to do on power
application. Your psu is trying to do this but the initial surge is too
much for it and it shuts down and then has another go. I've seen this
when a drive failed once and once when lightning took out the memory on
a system.

I think this is exactly what is happening. There definitely seems to
be a correlation between the initial surge and it failing as it did. If
you recall I could overcome this failure by allowing the LED on the PS
to turn off and immediately plug in the power cord again. I suspect the
standby voltage had started to discharge but not yet fully discharged
and that built up voltage overcame the surge.


You could try disconnecting the drives to see what happens but check
the 3.3v rail limits on the psu labels between your 250 and 350W psus.

I do wish I had thought of unplugging the hard drives and trying it,
but I have already sent off the computer.

It may just be the 5 and 12 volts that have extra current and the 3.3v
rails have the same limits. The memory uses the 3.3v rails [1] with on
motherboard regulators dropping it to what the memory needs, and it's
possible that the new memory is simply taking too much when when first
switched on. What I'm trying to say is that just because a power supply
is a higher wattage it doesn't necessarily follow that all rails have
the limits increased.

I'd want to run a memory test, such as Memtest86(+) for 24 hours though
to ensure that the memory wasn't damaged by inserting it with the
standby power on. The system gets the settings for the ram from a chip
on the ram module and if that's been damaged the defaults may be a
little high and overheat things after a while causing failures. If you
are running Windows then CPU-Z should be able to read and display the
ram configuration for you.

I have AIDA32 on both computers utilizing the PC3200 RAM, and the SPD
chip on each stick reads correctly. I did not run the memory test for
more than twenty minutes, but both computers are working perfectly with
the PC3200 RAM.

I admit that I do not have a problem, but a curiosity. One thing that
puzzles me however is the failure of the manual reset I wired in to
reset the logic during the failure I described. One would have thought
if anything were being read from the bios, that the +5 volts would need
to be up. If the +5 were up, then the reset would have also worked.
This is why I doubt that the wake by LAN or any bios setting could
account for the power starting and stopping every 1/2 second. I don't
think the +5 ever reaches that level. In fact I tend to believe the
standby voltage is also not up to an adequate level.

At any rate, I got some good suggestions and comments. The next time I
encounter such a problem I have a couple more ideas I might explore.
Thanks to all who commented.




[1] usually I think, at one time memory was run at 3.3v but nowadays it
seems to be around about 2v and I don't know if that's from the 3.3v
rail or the 5v rail regulated down.