Re: Boot Problems
- From: "Jan Alter" <bearpuf@xxxxxxxxxxx>
- Date: Fri, 25 Jun 2010 08:38:49 -0400
"Paul" <nospam@xxxxxxxxxx> wrote in message
In message <f8FUn.25694$m87.7282@hurricane>, Andy
"Nospam" <nospam@xxxxxxxxxxxxxxxxxx> wrote in message
My son's world has just collapsed!
His PC, home built has stopped working
After many year of use.
He has not added any new hardware, software or updates
It wont display anything on the screen at all. Not even the BIOS name,
should it display anything if we boot it with out a hard disc and no
I would have thought we would have a BIOS name then halt, I wouldn't
expect much with out ram but I would have thought we would have got
we have changed the graphics card as that was the only spare component
Sometimes the unit switches itself off a few seconds after switch on
some times it stays powered but no display
occasionally we have had a few successful entries into the BIOS but
mostly it is a totally blank screen
I have measured all the levels out of the PSU and they are in spec.
why would it turn itself off?
Or is the motherboard turning it off because it is not functioning.
Any suggestions most welcome
ASUS crosshair motherboard
4GBytes DDR2 800MHz Ram
320 GB SATA hard disc
The Asus Crosshair motherboard has a small lcd display mounted on the
back plate. You can view it from the back of the PC case near the
keyboard ps2 connector, it should give you some idea what the issue is.
The display just says
so its detected the DRAM but thats all it says.
I think the fact your computer switches itself off quickly, is just
as informative as being stuck at "DET DRAM". On a cheap motherboard,
the only reason for that to happen, would be an overheating CPU.
But since your board is a $250 enthusiast board, they could easily
have added other features to cause it to turn off.
I took a look over here, and found one report of bad caps on a board. The
board uses a mixture of polymer caps and electrolytic caps. The person
didn't say exactly which ones were bulging, but there were two
There were a couple reports of dead PCI Express slots, but that is par for
course with Nvidia chipsets. I've heard of PCI Express slots dying on them
That motherboard has an option to illuminate some blue LEDs, sort of like
maintenance lights. Apparently, when you press the button, it disconnects
+5VSB from the motherboard (which is normally monitored by a green LED
on Asus motherboards). That suggests to me, if you were to press that
the system was running, the blue LEDs would come on, and power would be
everything else. Check to see if the blue LEDs are lighting up, when the
power goes off. If so, it could be a defect in the LED lighting circuit,
which removes +5VSB from the board. The manual doesn't describe operation
that feature in enough detail, and I'm going on an off-hand comment from
a poster in the Asus forum.
One problem with getting excited about the Asus LCD display, is the
precision with which those codes are emitted. Looking at the page
of codes listed in the manual, the codes would seem to be based in
part on the Port 80 codes. But the listing isn't presented in the
sequence you'd expect to find the codes, so it's hard to say how many
other states it goes through, before getting to "DET DRAM".
To detect DRAM, requires that the Northbridge and Southbridge are
such that the SMBUS serial interface is operational. The processor uses
SMBUS (System Management Bus, 10KHz serial), to read the SPD chip on each
The BIOS gets RAM timings, to be used when the RAM is set to "Auto", from
The BIOS also gets the claimed memory size. Most of the other resources
by the processor, are inside the processor itself. Since this is an
board, the Vdimm regulator voltage may also need to be set. Your RAM
may be 2.2V (nominal 1.8V), so chances are your son has that setting
cranked to match what Crucial specified.
The BIOS has an alternate means of sizing the memory, and it actually
One person had a memory DIMM, where the SPD had incorrect information
the DIMM memory size, and the module still worked. And that means the
backup sizing routine runs as well as the SPD based method, so that the
BIOS will never commission memory that isn't really there (leading to
So depending on how many other display states occur before "DET DRAM",
tell you whether the chipset is working and so on. But seeing "DET DRAM",
means the BIOS has just entered that code. It doesn't mean the SMBUS is
working, for example. Perhaps some previous routine has set up the
chipset, which would be a positive sign. It would mean the board
isn't entirely dead.
The board is complicated, by virtue of the fact it seems to have two
monitor chips, many adjustable voltages and so on. A defect in one of
those adjustable voltage sources, would be enough to prevent POST.
The board seems to have its share of RAM compatibility issues, and
depending on available RAM on hand, you might try swapping in one
module of something else, to see if it'll get past DET DRAM.
Even doing a test, without any DRAM present for one testing cycle,
followed by plugging in one DIMM and trying again, may give
different test results.
My thought about turning the computer on and it briefly starting is the
notion that it has bad caps. When the PS starts a charge builds in the cap
(s) to begin it running, but the leak drops the voltage to initiate a
failsafe shutdown. Paul suggests that it could also be a partial failure of
the mb, which sounds like it could also be possible. Sorry I don't know more
to help you. Having a spare PS to try would help a little here.
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