it sounds like a system with incorrect bios part flashed on it.
may be wise to check if the fans are plugged in and running inside.
maybe wise to go into bios and select bios defaults and save / reboot.
if fans running go and get its official bios and flash that to it see if it goes quiet
if refuses its own bios a tool called uniflash can do unconditional program.
If all fails your motherboard could be dieing from internal fracture/ corrosion / signal degredation by component wear.
Voltage low could be poor mains conditions or even bad connection to motherboard but if its too bad it simply wouldn't boot which takes me back to incorrect bios looking for wrong place of power good signal.

So, I opened it up... I still don't know what's up with all the warnings, I think the fans are running... I mean I dunno what else could be making that noise tho, almost sounds like a jet engine...

It also looks really grimy and dusty. I feel like I need to strip this thing down and deep clean it before anything else. Feels dirty just turning it on.

https://imgur.com/a/VG97Vl6

It's kinda hard to see, difficult to get a good angle in there. It's one of those weird cases with a fold out compartment, like Dell does a lot. Guess they did so even as early as 2006. If anything looks off, let me know. I don't really see any big red flags at first glance, aside from the layers of dust.

Seems your new toy may have a bit of form for this!

https://www.google.com/search?q=dell+precisio … sclient=gws-wiz

Certainly needs a good clean but I suspect it won't help much - fingers seem to be pointing at either the cooling fan for the (toasty) FB-DIMMs or possibly developing thermal sensor faults causing the fans to max out all the time. There's even a utility available to try and combat the problems

https://www.diefer.de/i8kfan/

maybe the low voltage warning is due to dust contamination making the fans run at maximal destablilising the power rail of you power supply which could also be dirty inside.
If you do clean it up and it still loud as hell then i'd recommend a bios flash to be sure.
But as it is surely won't last long running. Perhaps its just screaming "clean me"
as far as sensors are concerned I never had that issue myself.

PC Hoarder Patrol wrote on 2021-10-29, 21:40:

Seems your new toy may have a bit of form for this! […]
Show full quote

Seems your new toy may have a bit of form for this!

https://www.google.com/search?q=dell+precisio … sclient=gws-wiz

Certainly needs a good clean but I suspect it won't help much - fingers seem to be pointing at either the cooling fan for the (toasty) FB-DIMMs or possibly developing thermal sensor faults causing the fans to max out all the time. There's even a utility available to try and combat the problems

https://www.diefer.de/i8kfan/

Interesting good find

Heres a tool that can adjust fan speeds manually or automatically via user calibration http://www.almico.com/sfdownload.php
Works with many motherboards even laptops where sometimes loud is better as well as quiet as a mouse where desired

I would be inclined to give it a good clean and then get some numbers for the Temperatures, Voltages and Fan Speeds. Below is what I see on my Dell 490.

In terms of the BIOS then mine has BIOS A08 04/25/2008 which AFAIK is the latest.

I can't seem to get it to boot at all, unfortunately. After that long list of warnings it just hangs on that screen.

I pulled out the hard disk and checked it out, apparently there's Windows 7 on there. But I think the machine hasn't been actively used for the last 5 years or so.

red-ray wrote on 2021-10-29, 22:06:

I would be inclined to give it a good clean and then get some numbers for the Temperatures, Voltages and Fan Speeds. Below is w […]
Show full quote

I would be inclined to give it a good clean and then get some numbers for the Temperatures, Voltages and Fan Speeds. Below is what I see on my Dell 490.

In terms of the BIOS then mine has BIOS A08 04/25/2008 which AFAIK is the latest.

Got a question, thought you might know this... There's another fold out compartment near the card slots you're supposed to be able to fold out to expose the screws keeping the cards in place. But in this thing, the little blue handles are broken off. Do you know of a way to get around that? I tried to force it out, but the thing won't give an inch.

JustRob wrote on 2021-10-30, 15:43:

the little blue handles are broken off. Do you know of a way to get around that?

The red arrows show where the missing blue handles should connect to so I suspect you could use two small screwdrivers to to push them towards each other and then if you wiggle it back and fourth it will release, but I suspect you will need at least three hands to do this!

My 490 has the blue handles and even with them I needed to wiggle it to get it to release

I just booted it up and today it's much cooler, but I suspect to will warm up after a while.

Ugh, that blows. I really dislike those blue plastic brackets in Dell cases. They have a tendency to break easily, as apparently happened in mine.

Maybe I can glue some small metal pieces on it and make a makeshift handle. Thanks anyway.

Well, I managed to get it open using the screwdriver method. Wasn't pretty, but it worked.

Now to the next thing... this might be a stupid question, but do you know how to remove the drive bay? I'm trying to get the dvd-rom drive out of there. There's another blue plastic slidy thing that moves, but it doesn't seem to do anything.

I wish I could find a teardown of this PC... nothing useful on google or youtube. This thing's like a puzzle box.

If it is like some Dells I have worked on you press the blue handle down and slide the drive out. Sometimes it requires a bit of wiggling, and you should hear a snap/pop as it moves out of the lock position.

JustRob wrote on 2021-10-30, 18:38:

How do you know how to remove the drive bay?

Basically you need to remove the front panel, pull the blue leaver towards you and push the front panel up.

Next push the Blue Thing up and remove the black surround. You also need to push the blue thing up to allow the drives to be removed.

red-ray wrote on 2021-10-30, 20:13:

JustRob wrote on 2021-10-30, 18:38:

How do you know how to remove the drive bay?

Basically you need to remove the front panel, pull the blue leaver towards you and push the front panel up.

Next push the Blue Thing up and remove the black surround. You also need to push the blue thing up to allow the drives to be removed.

I got it, thanks. I didn’t realize you could take off the silver front thing, thought it was hard-bolted on there. I’m glad I was wrong about that tho, cuz the backside of that is very dusty and grimy. That would’ve been a pain to clean that otherwise.

Man… i hope i can put this thing back together after cleaning it, lmao

JustRob wrote on 2021-10-30, 20:18:

I got it, thanks. I didn’t realize you could take off the silver front thing, thought it was hard-bolted on there. I’m glad I was wrong about that tho, cuz the backside of that is very dusty and grimy. That would’ve been a pain to clean that otherwise.

Man… i hope i can put this thing back together after cleaning it, lmao

The official user's guide might help a little, if you haven't downloaded it already.

dormcat wrote on 2021-10-31, 04:57:

JustRob wrote on 2021-10-30, 20:18:

I got it, thanks. I didn’t realize you could take off the silver front thing, thought it was hard-bolted on there. I’m glad I was wrong about that tho, cuz the backside of that is very dusty and grimy. That would’ve been a pain to clean that otherwise.

Man… i hope i can put this thing back together after cleaning it, lmao

The official user's guide might help a little, if you haven't downloaded it already.

Someone messaged me about this, you're right, this helps a ton.

There's an Nvidia Geforce 8800 GTX in here. Anyone know if the system came with that originally?

It's dusty as all hell, and it's kinda hard to clean the fan. Tried canned air, but my canned air is pretty cheap and doesn't have the long straw like some others. Can't really find a teardown guide, so I guess I'll just take out all the screws and take pictures as I go... If anyone has general advice on how to get fans clean without complete disassembly, that'd be appreciated... most google results suggest canned air, but mine doesn't work very good, or fiber cloth, but it's hard to get cloth inside those tiny spaces.

Doubt it - the original configurator only lists...

NVIDIA Quadro® FX 4600 / supports 1 or 2 dual link connections / High-End
NVIDIA Quadro® FX 4500 / supports 1 or 2 dual link connections) / High-End
NVIDIA Quadro® FX 3500 / supports 1 or 2 dual link connections / Mid-End
NVIDIA Quadro® FX 3450 / supports 1 dual link connection / Mid-End
NVIDIA Quadro® FX 550 / Entry 3D
NVIDIA Quadro® NVS 285 (128MB) / Entry 2D

FireGL (TM) V7200 / supports 1 or 2 dual link connections / Mid-End
FireGL (TM) V3400 / supports 1 dual link connection / Entry

That's interesting. Aren't those newer than the Geforce 8800 GTX? Why would someone wanna put an older graphics card in there?

Oh well, should work fine still for a Windows XP box. After it's cleaned up.