Re: Troubleshooing advice, please...

On 3/21/2024 6:44 PM, Nil wrote:
> Lotsa interesting info here, thanks. I've been poking at this thing all 
> day with no joy. I can verify that the old PS is dead - no voltage on 
> any pins, no matter what. I can verify that the new PS is good - it's 
> one of the ones you mention that the fan doesn't come on unless it 
> heats up to a certain temperature, but the expected voltages are on all 
> pins, including the CPU connector. But that's as far as it goes. The 
> motherboard has some lights on it that glow when the PS is connected 
> and turns on, but nothing else happens, no fans, no drives spinning up, 
> no display, not a peep or twitch. I can only conclude that the mobo has 
> failed. Probably the PSU killed it while itself dying. Murder-suicide.
> 
> I wonder if it's possible that the PSU might test good with the 
> multimeter but can't power up mobo + peripherals when all loaded up?
> 
> This is a bummer - I've always enjoyed building PCs for myself, but 
> I've always known the current machine was ready to be replaced and I 
> had time to leisurely deal with it. This is a catastrophic failure and 
> I'm in the middle of some projects and don't have time to research and 
> gather components for a new build. I'm inclined to go buy a Dell or 
> something off-the-shelf.

In the old days, I would have taken a clamp-on DC ammeter and
checked what kinds of currents were being drawn. It it was
doing that (drawing a lot of current), there would likely be
some other symptoms. But you would probably need an IR camera
to locate where the power was going, without a DC ammeter.
The nice thing about clamp meters, is there are no fuses to blow
on the instrument :-)

If it wont start, you could have a grounded RESET wire to the
front panel. Or, a Power_Good signal from one of the onboard
regulators, is indicating it is Not Ready, and the CPU stays
in the reset state if that is the case.

With modern kit and all those black wires, it's pretty hard
to tell what is what (when positioning the clamp meter, and having
a wrap around the wires that needs to be cut.

Even when I bought a 24-wire extension cable,
the fools used colored wire, but did not assign standard pins
for the colors, so the coloration was of no use.

*******

You have some DDR4 in hand. You could look for a different solution,
and try to reuse the RAM at least.

A lot of the boards now, no longer have a PCI slot. They may still have
a kbd/mouse PS/2 hole, for at least one of the two appliances to go. Some
even have a serial RS232 port. Both my machines have RS232, even though
it was hardly advertised as being present. On one machine, I just noticed
it one day while examining USB2 headers, and I noticed "one header has a
strange pinout". And that was an RS232 when I looked it up.

The PCI Express slots may not be as useful as before. Before, we had
x8/x8 on two slots, and bifurcation logic. Today, the mainstream
boards are still sporting x16 on one slot (no external logic for it),
and x4 (off the PCH) for the second x16 slot. The bandwidth is not shared any more,
to the same extent it once was. Any arch changes, the extra lanes are
used for NVMe devices, rather than as card slots.

You have to watch modern machines, for how they're doing VCore. The
heatsinks are too small. The processor draws over 200W under turbo,
and this stresses the VCore a bit. I prefer to add cooling so
it is less stressed, but, they don't make it easy. To do it properly,
I'd have to change cases to make room for a fan in the right position.
On the Test machine, I did a kind of "blower", mounted off the
end of the drive bay, to get cooling onto VCore on that one. I burned
my finger on VCore while testing on the kitchen table on the Test Machine,
and that's when I determined I had not made a clever product choice.

If you get a Dell or an HP, you know the VCore is going to be
"even thinner". And at least in the case of Dell, the BIOS is
likely to be some sort of unacceptable piece of work.

I guess I still prefer to build, but for slightly different
reasons than before. Getting a good BIOS is part of the puzzle,
one with settings that work.

A relatively cheap way to build a system, would be a good AM4 board,
an AMD Zen3 5600G, and your DDR4 RAM reused. But I suspect the 5600G
are out of production, because they're too cheap and don't make
AMD enough money. You could go upscale a bit, and get the one with
additional L3 on it.

   [Picture] 5600G

   https://i.postimg.cc/BZYR3B7x/cpuz.gif

Another thing to watch, is the CPU cooler. The 5600G system in that
picture, it uses the stock aluminum cooler. the adaptive cooling
system in the BIOS, doesn't even modulate the fan at all, because
there isn't enough stress for it to track what is going on.

When you put a 200W CPU in there, the instructions say "AMD recommends
a water cooler". I thought this was some kind of joke, but if you
want the Turbo to get close to the "rating on the tin", it really
appears you do need water.

For a cooler, I decided to skip the Noctua and tried a AK620 Zero Dark
(deepcool.com) and it was a bit cheaper than a Noctua would have been.
And it actually handles the heat OK. If the cooler is under-sized on
a high power processor, you might see weird "thermal spikes" in a
temperature trace. With the more capable cooler fitted, the control loop
settles right down. With water, I would guess I'd get more than 4.55GHz,
but not enough for me to want water inside the poor thing. I guess I
just like air cooling.

   [Picture] 5950x at idle and full power (62C) on Deepcool AK620

   https://i.postimg.cc/XJbVph8f/power-control-recent-CPU.gif

You don't get to use the cores all that often, and I got the
setup just for 7ZIP.

   [Picture]

   https://i.postimg.cc/RVJz4kZC/cpu-flat-out.gif

It still takes all day, to compress a backup file. And at
224W wall power measured, you only want to be doing that
sort of compression in winter, when the air is cooler in here.

Maybe an Alienware would give you some of the properties of
an enthusiast machine, but then you're paying $1000 more for
the name (like "Cadillac").

With your experience, I'm sure it won't take you that
long to pick something.

   Paul