micky said:
I find RAM tricky to install. I haven't read all the replies, but
someone should point out:
Obviously, you want the notch in the RAM stick to correspond to the
plastic, unslotted portion of the RAM socket.
Not so obviously, put the stick in at about 30 degrees from vertical,
After it's in as far as it goes, then push it upright.
I've found it requires a bit of pushing, usually on one end and then on
the other (though I've often wondered if it would work to push on both
ends at the same time.) Hmm. I thinkt the pushing is when it's still
at 30^, but there is a hole in my recollection.
Well, it's been years since I've done this and I realize my memory has
at least one hole. If I'm wrong, I'm sure someone will correct me.
The key and notch system is intended to try to weed out improper
mixtures of memory DIMM versus "motherboard+slot_type". They
didn't invent the scheme, with the express wish to have it
defeated by tilting the DIMM at a 30 degree angle and forcing it.
Or as one clever individual claimed in a USENET posting, he
"sawed a slot in the DIMM to match his motherboard", surely a hint
"you're doing it wrong"
What you really want, is installation in a well-lit environment.
I use a halogen lamp with adjustable arm, when I need to see
inside a PC. That allows eyeballing the slot and the DIMM,
and figuring out "which way is back or front". It's possible
to rotate a DIMM by accident, but the key should help prevent
that.
The key position can also indicate registered versus unbuffered
DIMM. It could indicate voltage (where there is a possibility
of damage by inserting the wrong thing). And the JEDEC committee
should be comparing dimensions and already allocated keying
positions, with the intention of preventing accidental insertion
(shoving FPM or EDO into DDR4 slot or vice versa).
Some DIMM slots do indeed require both tilting and fiddling,
and I cannot recommend such slots. The last motherboard I bought,
used multi-colored plastic to hide the fact the DIMM slots
were "one ejector" designs, instead of a proper "two ejector"
design. One end of the DIMM is always effectively locked, and
there is no mechanical means to ease it out of the slot. The
other ejector does all the work. The purpose of this
design, is to allow video card slot #1 to be pressed right up against
the end of the DIMM slot. Since the (fixed) end of the DIMM slot
has no moving ejector, you don't have to remove the video card
to actuate the ejector. Instead, the plastic on that end is just
fixed. When the maker of the slot is "honest", they use a single
solid color (say, yellow) for the entire DIMM slot plus the fixed
function on the video card end of the slot. By using a different
colored plastic for the fixed end, you can "fool" people like
Paul into thinking the slot comes with a real ejector on that end,
when it does not.
1) Present the DIMM equally to both ends of the slot. Don't
tilt at an angle.
2) Using a bright light, compare the key (not properly colored)
to the slot.
3) Once you've checked, checked and rechecked that you aren't
doing something stupid, *now* you can start tilting the thing
if you have one of those one-ejector slots.
Some low-profile DIMMs resist even proper insertion, because
the bevel of the PCB board is too "blunt" for easy insertion.
The Kingston low profile DIMMs for example, hurt your fingers
while you're pressing them into place. Taller DIMMs, use a
different milled profile on the edge of the PCB, where it
goes into the slot.
4) For a small number of motherboards (perhaps mixed DDR400/DDR2
boards), the board actually includes a jumper to select operating
voltage. You get to choose one RAM type of two slot types
available (two DDR400 slots, two DDR2 slots). The keying system
ensures you use an acceptable kind of RAM with the motherboard - but
it does not detect two different types installed at the same time.
It also doesn't detect that the jumper setting is applying 3.3V
to a 2.5V memory. So those motherboards, for a naive user, are
a mine field. Anyone attempting a build with ancient motherboard
stock of that type, where the "manual happens to be missing",
runs the risk of blowing the thing. Due to the insistence of the
maker, on not putting an interlock in place. Even when I've read
the manual on some of those, the function of the voltage
jumper may not be documented properly.
Some of those, the voltage setting is auto-detected, so
no damage can result. But a few were designed to aid in
"accidental destruction" of the motherboard. Such boards
are usually the $65 variety.
HTH,
Paul
