species8350 said:
Just checked the diagnostic lights.
After they stopped flashing, the stable condition is no lights for the first two, and green for the last two.
According to the manual this means faulty RAM
Previously, I tried removing one RAM module and switching on, but it would not boot. I tried this module in the other slots, but no luck. I repeated this for the second module with the same result.
Can I confirm that it is a RAM problem (from my tests it looks doubtful - it would mean that both modules are faulty - unlikely).
Thanks
It's unlikely both DIMMs would be bad at the same time, if
it was a DIMM fault.
Standard practice would be, to find another compatible DIMM,
and test it in the motherboard, and see if the symptoms change.
For both DIMMs, tested individually, to give faults, it's
more likely the VDimm regulator isn't working, or something
related to the Northbridge (Vnb for example). In other words,
a bad motherboard.
But the fact that the screen lights up, and starts to paint
the animated bar, means much of the chips is working. That's
the symptom which doesn't make much sense. A "solid" RAM failure,
should have given a black screen at startup. Not the green bar
on your screen. To get the green bar on the screen, the system
would have to be 99.9% working.
If the BIOS is running a RAM test, it could certainly find an
error in the upper areas of memory (above where the frame buffer
image is stored, at some location like 0xA0000). But what are
the odds, that both DIMMs have bad locations, suddenly detected
at the same point in time, such that either of the DIMMs
tested individually, give the same symptoms ? That part, just
doesn't make sense.
Maybe the error code is "bad RAM", but in fact it's some other
fault entirely, and the BIOS is just... nuts.
*******
You could take the side off the machine and inspect the
capacitors. Those are cylinders with a plastic sleeve over
them. Look for signs of bulging (related to internal pressure)
or leaking of electrolyte from inside the capacitor. Older
motherboards use aluminum electrolytic capacitors. More modern
boards use solid polymer capacitors. The solid polymer ones,
don't have pressure relief seams on the top of the capacitor,
implying there is less chance of pressure buildup with the
solid electrolyte.
There is nothing really wrong with the usage of aluminum
electrolytics. They're perfectly good. It's because billions
of them were made improperly, that we have a problem with them.
The introduction of solid polymer ones, to take their place,
is a "face saving" move by the motherboard manufacturer, a way
of saying "well, you can see we don't have any bad caps, because
they aren't the wet electrolyte type any more". If all the capacitors
were properly made, the older style cap with the pressure seam
on top, could have continued to be used. Some Dell models, had
a tremendous dropout - virtually all the motherboards failed
due to that problem. To such an extent, certain Dell models
are not safe to buy, used, on Ebay.
Here is a background article on the issue.
http://en.wikipedia.org/wiki/Capacitor_plague
Your machine is relatively modern, and the newer the machine
is, the less likely it is to be a capacitor problem. There are
still motherboard companies using bad materials, but becoming
less and less every day. There was a large inventory of bad
product out there, and the motherboard makers have to invest
effort in preventing the bad capacitors from going into products.
Paul
