Asus M2NPV-VM motherboard Power-On Self-TEST (POST) problem whenchanging disks (etc)

[reikred]

(this post is a cousin of my other recent post, but the question is
different, so I am starting a new thread).

Twice in the last month I have had occasion to swap some hardware
component of my Asus M2NPV-VM -based PC. In both cases, there were
some severe problems getting the system to pass POST after the
hardware exchange.

Case1 was adding an "external" PCIE VGA card (geforce7200) to supplant
onboard VGA (geforce6150)

Case2 was upgrading the hard drives

In both cases, the POST hangs before getting to the point where there
is any VGA output. That is, the pc will hang with a blank screen.
There is no indication what is wrong (no audible POST codes on the
speaker, and since no Port 80 LED display, also no other inidication).

In order to get past POST, I had to go through some serious gyrations
involving disconnecting all peripherals on the motherboard side,
taking out the CMOS-RAM battery, clearing CMOS-RAM by moving a jumper,
even shorting the battery socket terminals due to lingering voltage on
the terminals, etc etc etc (insert lots of black magic here).

Now, in the case of the external VGA card, one should perhaps expect
some minor trouble since BIOS has to figure out which VGA destination
to use, but why on earth would changing a DISK cause such a problem?
I'm completely baffled by the amount of black magic and weird things I
had to apply to get a simple POST.

What might be going on here?

 

[reikred]

What make and model power supply?  I suspect you're running
out of juice with these upgrades.  With a barely capable PSU
you might find it randomly manages to POST or fail, so many
different things might seem to help once but not the next
time.

Thanks Kony. I don't think it is the power supply, because
once I get past the problem the system will boot flawlessly
every time, any number of times, and the system as a whole
is solid.

 

[reikred]

Sorry. I meant to say:

....once I get past the problem the system will POST *AND* boot
flawlessly every time, any number of times, and the system as a whole
is solid.

That is why I do not think it is a power supply problem. I can cycle
the power switch (even the one back) any number of times and I will
get a rock solid POST and boot every time, once the system (BIOS or
whatever it is) gets into a good state. My suspicion has always been
that there is a BIOS problem. I have installed the latest BIOS, by the
way.