Nice find Clueless! That should be a fun little system. Heck it is fast enough to use as a daily web browser 🤣.

Tetrium wrote:

Too bad I destroyed the board when I tried to power it up with it's CLEAR-CMOS jumper installed...magic smoke and that was it 😢

Aren't you supposed to do that? Most boards I've used won't clear the CMOS until you power them on with the clear CMOS jumper installed.

Malvineous wrote:

Tetrium wrote:

Too bad I destroyed the board when I tried to power it up with it's CLEAR-CMOS jumper installed...magic smoke and that was it 😢

Aren't you supposed to do that? Most boards I've used won't clear the CMOS until you power them on with the clear CMOS jumper installed.

Are you sure? Which boards were these?
I've actually read the A7V333 manual and it states it's only to be shorted while the system is unplugged

Tetrium is correct.
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The power supply should be powered down all the way to the AC side to reset the CMOS.
If the PSU does not have an AC switch it should be unplugged from the wall.
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The CLEAR-CMOS jumper basically shorts the BIOS chips power (battery) to ground.
It makes no sense to do that while giving it an alternate power source. It would never clear.
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Are you sure about that? If you short those lithium batteries there is a chance it will overheat so that seems like a bit of a risky solution. I always assumed one of the very first things the BIOS did was check whether the jumper was opened or closed, and if it was open it would load the settings from NVRAM, but if it was closed it would load defaults instead and write them to NVRAM, then halt.

Here's the instructions from Dell which say AC power must be supplied for at least 10 seconds or the clear CMOS jumper won't work and my L440GX+ manual (page 60) says that the BIOS scans the CMOS reset jumper during boot. So perhaps not all motherboards work this way, but there are certainly some out there that do. My GA-6BXC manual doesn't mention anything about how the jumper is meant to be used, but it doesn't warn you against powering the system on while it's set.

Certainly I have always turned the systems on in the past when I've done this, as I found that they often don't wipe the CMOS unless you do. When you switch them on with the jumper connected, they don't POST, but switching them off again and removing the jumper returns them to normal, with default CMOS settings. You tend to get an error message along the lines of "Default settings loaded" as opposed to removing the battery for a while which tends to result in "CMOS checksum invalid" instead, which suggests more is happening than just zeroing out the NVRAM.

I have also replaced CMOS batteries without losing any settings, so I would guess that if all the jumper did was short the battery, there's no guarantee that would erase the settings.

Malvineous wrote:

Are you sure about that? If you short those lithium batteries there is a chance it will overheat so that seems like a bit of a […]
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Are you sure about that? If you short those lithium batteries there is a chance it will overheat so that seems like a bit of a risky solution. I always assumed one of the very first things the BIOS did was check whether the jumper was opened or closed, and if it was open it would load the settings from NVRAM, but if it was closed it would load defaults instead and write them to NVRAM, then halt.

Here's the instructions from Dell which say AC power must be supplied for at least 10 seconds or the clear CMOS jumper won't work and my L440GX+ manual (page 60) says that the BIOS scans the CMOS reset jumper during boot. So perhaps not all motherboards work this way, but there are certainly some out there that do. My GA-6BXC manual doesn't mention anything about how the jumper is meant to be used, but it doesn't warn you against powering the system on while it's set.

Certainly I have always turned the systems on in the past when I've done this, as I found that they often don't wipe the CMOS unless you do. When you switch them on with the jumper connected, they don't POST, but switching them off again and removing the jumper returns them to normal, with default CMOS settings. You tend to get an error message along the lines of "Default settings loaded" as opposed to removing the battery for a while which tends to result in "CMOS checksum invalid" instead, which suggests more is happening than just zeroing out the NVRAM.

I have also replaced CMOS batteries without losing any settings, so I would guess that if all the jumper did was short the battery, there's no guarantee that would erase the settings.

Dell (and other large OEMs) have always (or at least on a regular basis) given their hardware a twist of their own though. I remember having worked on a FS s370 motherboard which had trouble booting. And the fix? ...add a coin cell battery! 😁

Scored some free stuff lately, first up this bad boy from the side of the road. Ugly as sin early 2000's case in excellent condition - answers to 'Capricorn' apparently. Inside was a working ASUS P4SGX-MX and 2.6 GHz Northwood Celeron. The HDD was neatly wrapped in duct tape and smashed to smithereens – I guess people are getting better with privacy issues.

Next up this monstrosity from my brother in law. The case will go to god but I'll keep the Athlon 64 3200 / ASUS A8V-MX combo that it came with:

And lastly a couple of gfx cards from my father in law, an ‘ATi Radeon 9800 Pro’ and a ‘Geforce 8800GT’. In need of a clean but otherwise A-OK:

clueless1 wrote:

Technically, not a dumpster find. But someone brought me a PC, asked me to retrieve all the pics and docs off of it, then do wh […]
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Technically, not a dumpster find. But someone brought me a PC, asked me to retrieve all the pics and docs off of it, then do whatever I want with it. So it was destined for the dumpster as far as I'm concerned!

It is a Dell Optiplex GX270, circa 2004. Specs:
P4 2.8/512k/800 (hyperthreading disabled in BIOS)
1GB (2x512) DDR400
40GB IDE
Intel Extreme Graphics (i865)
onboard SoundMAX audio
It has some scuff marks on the outside and dust bunnies on the inside, but otherwise it is in pristine condition. And it appears to have been hardly used at all. Hardly any software on it, completely free of malware. It was so clean I just uninstalled a few apps (Adobe Reader 7, AVG, etc), deleted the user profile, ran Windows Update and it was like a freshly installed OS.

Updates done to it:
updated BIOS, then turned on Hyperthreading
replaced the RAM with 2x1024MB DDR400
imaged the drive to a 160GB SATA for more room and a little more speed
And the best part: it has an AGP 8X slot, so I finally found a home for my GeForce 6800GS AGP! Here are the christening photos:

3dmark03.jpg

3dmark05.jpg

Quite sure those GX270's suffers from the cap plague, had a GX280 as HTPC that definitely did a bunch of years ago. You might want to consider recapping the mobo if you intend to keep and use it.

By the way, at least the GX280 got an extremely noisy radial CPU fan, sounds like a jet plane with some CPU load. Did a simple mod to my 280; opened up a hole in the upside part of the case, and installed a slim profile 120 mm intake fan with a resistor dimensioned to drop the 12V feed down to 9V or something like that to keep the rpm down a bit. After that the CPU fan barely even spun up, even at 100% load.

Malvineous wrote:

Are you sure about that? If you short those lithium batteries there is a chance it will overheat so that seems like a bit of a risky solution. I always assumed one of the very first things the BIOS did was check whether the jumper was opened or closed, and if it was open it would load the settings from NVRAM, but if it was closed it would load defaults instead and write them to NVRAM, then halt.

Yes I am sure.
You falsely assumed I meant a dead short to ground. It's not. That's why I used the word effectively and why it doesn't happen instantly.
There are caps, resistors & diodes in the circuit. They isolate the battery from ground while allowing the BIOS chips power pin to be discharged.
If you leave the jumper on for an extended time it will drain the battery completely but the other components (and jumper location in the circuit) slow that down while allowing the BIOS pins voltage to go to zero, or close enough.

Malvineous wrote:

Here's the instructions from Dell which say AC power must be supplied for at least 10 seconds or the clear CMOS jumper won't work and my L440GX+ manual (page 60) says that the BIOS scans the CMOS reset jumper during boot. So perhaps not all motherboards work this way, but there are certainly some out there that do. My GA-6BXC manual doesn't mention anything about how the jumper is meant to be used, but it doesn't warn you against powering the system on while it's set.

What I said was clearly only pertinent to normal systems that use a CLEAR-CMOS jumper.
Those you brought up (above quote) don't use a jumper so how are they even applicable?
For things like this there is always going to be some weird circuit magic someone did that isn't typical.

Doing it without a jumper requires additional circuitry and is usually the same as resetting to defaults from within the BIOS and then rebooting.
That does not always completely clear NVRAM and using a usually jumper does. It may only clear select portions.
I dunno how Dell is doing it but Intel uses BMC which is in effect a secondary BIOS (firmware) that handles other functions needed for servers.
The BMC has a function to reset the BIOS on your board. That's what you are reading on page 60-ish.
It actually says (in different words) that following that procedure is the same as using the jumper. (So clearly there is a jumper option.)
If you dig deeper into your Intel manual you will find 4 or 5 jumpers associated with resetting the BIOS and/or BMC and one of them determines if BMC has the ability to reset the BIOS. Intel server boards are like that. Gets confusing really fast. Normally you have to do two BIOS updates, one for the BIOS and another for the BMC.

In the future if you want me to look in a manual please provide a copy or a direct link to a PDF or doc it so I don't have to go find it. Legacy Intel is particularly annoying as you have to download and unpack a zip which in this case gives 88 PDF files many of which are just numbered rather than having names.

Malvineous wrote:

Certainly I have always turned the systems on in the past when I've done this, as I found that they often don't wipe the CMOS unless you do.

Um, Lost me. If you don't turn it back on how do you know if it cleared or not?

Malvineous wrote:

When you switch them on with the jumper connected, they don't POST

That's because the power to the BIOS chip is shorted so it can't run the POST code.

Malvineous wrote:

, but switching them off again and removing the jumper returns them to normal, with default CMOS settings.

That's because when you remove the jumper the power to the BIOS chip is restored so it can run the POST code.

Malvineous wrote:

You tend to get an error message along the lines of "Default settings loaded" as opposed to removing the battery for a while which tends to result in "CMOS checksum invalid" instead, which suggests more is happening than just zeroing out the NVRAM.

If you have fully reset (cleared) the NVRAM you will get that message. If you have only reset it to defaults you might not.
"RESET" and "CLEAR" are are used interchangeably (even in manuals/docs) but they aren't always the same thing.
Getting the message or not depends in part on how well the BIOS autodetects as it starts and if the time clock was reset.

Malvineous wrote:

I have also replaced CMOS batteries without losing any settings, so I would guess that if all the jumper did was short the battery, there's no guarantee that would erase the settings.

Some systems have enough capacitance in the battery circuit to hold the BIOS up long enough to change the battery.
The jumper overcomes that and that's another reason the procedures say to leave the jumper on x-amount of time.

~~
I don't know at what point in history they stared doing this but many systems have an auctioneer-switch type circuit to power the BIOS.
For ATX when the PSU is *powered* the BIOS gets power from +5vsb and the battery is cutout or auctioneered off.
For AT (and maybe some early ATX) when the PSU is *on* the BIOS gets power from +5v (or 3.3v) and the battery is cutout or auctioneered off.
(Yeah, it's stepped down. - Before someone asks.)
They do this to extend battery life by not using it when other power for the BIOS is available.
- So, if you have an ATX PSU and this feature a jumper reset isn't going to work if the PSU has AC power to it as the BIOS is not being powered by the battery anyway.
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kaputnik wrote:

Quite sure those GX270's suffers from the cap plague,

Wellll, yes and no. - Depends on how you define capacitor plague.

Wikipedia seems to think the capacitor plague is all about the stolen electrolyte formula fiasco (and nothing else).
But that only affected some Ch/Tw brands of caps and Dell didn't use Ch/Tw brands. Least not in Optiplex.
[Wikipedia is actually wrong multiple times in that article. Is a problem when clueless Academics take the word of News Reporters over Techs.]
This problem only lasted 3 or 4 years (in so far as when the caps were produced) and supposedly only affected 11 brands of Tw caps.
No one was willing to say -which- 11 brands. Probably didn't want to get sued.

Others seem to think the capacitor plague is all about the impurity issues with Aluminum sourced from Chinese mines.
(As discovered by a failure analysis lab at the University of Maryland when they were studying the above electrolyte problem.)
This also only affects Ch/Tw brands of caps. Dell didn't use Ch/Tw brands. Least not in Optiplex.
This problem affects all brands of Ch/Tw caps and is still going strong. It's why one should buy Japanese caps.

The capacitor plague that did affect Dell was the problems with defective Nichicon HM and HN series caps. (A Japanese brand.)
These were due to back to back problems at their factories and affected caps were made from 2001-2004 or 2005.
Also Chemicon, another Japanese brand, KZG and KZJ series (all of them) have issues.
This one affected Dell, Apple, Intel and basically everyone else that used Jap caps at the time.
For Optiplex it affected from the late SX/GX260 models to the early SX/GX280 models.

The SFF and USFF cases like those models used also have heat issues bad enough to blow any kind of cap.
In a way of thinking that could be considered as another capacitor plague.
That has been seen at least up in to the 745 and I think 755 models.
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Yup, Malvineous is right. A more common and more recent board, GA-7n4oos, also requires me to power up for several seconds before CMOS defaults are loaded. Does not work without powering up.

RacoonRider wrote:

Yup, Malvineous is right. A more common and more recent board, GA-7n4oos, also requires me to power up for several seconds before CMOS defaults are loaded. Does not work without powering up.

Yeah ..... You do have to turn it back on to load defaults.
You obviously aren't going to load anything if it's turned off.
Maybe I don't understand what you are trying to say.
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Here what your manual says - page 77.
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It's not worded well but steps 3 and 4 are where you would short with the jumper if you use that method vice removing the battery.
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I think disconnecting the mobo power cable is a bit excessive but it makes it pretty clear they want no power to the board while you power down the BIOS chip.
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PCBONEZ wrote:

Yeah ..... You do have to turn it back on to load defaults. You aren't going to load anything if it's turned off. . Here what yo […]
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RacoonRider wrote:

Yup, Malvineous is right. A more common and more recent board, GA-7n4oos, also requires me to power up for several seconds before CMOS defaults are loaded. Does not work without powering up.

Yeah ..... You do have to turn it back on to load defaults.
You aren't going to load anything if it's turned off.
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Here what your manual says - page 77.
.

CMOS1.jpg

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It's not worded well but steps 3 and 4 are where you would short with the jumper if you use that method.
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I think disconnecting the mobo power cable is a bit excessive but it makes it pretty clear they want no power to the board while you power down the BIOS chip.
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Are you even reading what you provide as an argument? This fragment is about clearing CMOS by removing the battery, not using the jumper. They don't want you to even open the case with power plug connected for obvious reasons.

RacoonRider wrote:

Are you even reading what you provide as an argument? This fragment is about clearing CMOS by removing the battery, not using the jumper. They don't want you to even open the case with power plug connected for obvious reasons.

Clearly I'm reading the thread much more diligently than you read your manuals because this is what started it.

Malvineous wrote:

Tetrium wrote:

Too bad I destroyed the board when I tried to power it up with it's CLEAR-CMOS jumper installed...magic smoke and that was it 😢

Aren't you supposed to do that? Most boards I've used won't clear the CMOS until you power them on with the clear CMOS jumper installed.

It's about the jumper, and what happens when you use it. - Not the battery.

And you very own manual gives the typical standard procedures - which is what I've been talking about all along.
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Your manual specifically says to disconnect the power cable from the motherboard.
How are you supposed to do that without opening the case?
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PCBONEZ wrote:

How are you supposed to do that without opening the case?

Nanobots

PCBONEZ wrote:

RacoonRider wrote:

Are you even reading what you provide as an argument? This fragment is about clearing CMOS by removing the battery, not using the jumper. They don't want you to even open the case with power plug connected for obvious reasons.

Clearly I'm reading the thread much more diligently than you read your manuals because this is what started it.

Don't mind RaccoonRider, he doesn't like being proven wrong and can get pretty pissy if you don't leave him to live in his own delusions. You may as well just give up because he and Swayee are so far up each other's ass I thought they were horribly deformed conjoined twins. Besides, it'll be his hardware that gets fucked up at the end of the day, you tried to post useful facts and people didn't listen - their loss.

PCBONEZ wrote:

What I said was clearly only pertinent to normal systems that use a CLEAR-CMOS jumper.
Those you brought up (above quote) don't use a jumper so how are they even applicable?

It don't use a jumper??

Malvineous wrote:

(page 60) says that the BIOS scans the CMOS reset jumper during boot.

You need to calm down PCBONEZ.

Here at VOGONS your retro computer cred is safe, nobody is going to think less of you for not knowing something, or for thinking the wrong thing about something. It happens.

A simple "Oh, so there are exceptions to the rule, weird!" would have sufficed. There was no need to get hyper defensive, and more generally there's no need to concoct "No true Scotsman" scenarios to demonstrate that you are right.

PCBONEZ, you know what I mean. Despite what the manual might say, with my exact board it only works the way Malvineous described.

HighTreason, insults again... Is being a dick all you are capable of?

Hey, apparently you're above being accountable for your actions, so therefore I must be so as well.

I could sit here and point out everything wrong with the situation you've dug yourself into, but I can't be bothered because I've got to go out soon. Still, do you want to know the difference between you and I? The difference is, I admit to being a dick - in fact, I think I said so in my very first posts on these forums - and by extension, I accept when I am in the wrong or when I've done something particularly "dick-ish" that was out of line. I know my own faults, which is why - for example - I don't post on forums for a few hours after I wake up because I'm not particularly civil when I'm half asleep.

Just to bug people of even more I have to add that on many motherboards the clear BIOS jumper seems to disconnect a battery lead. In most cases the jumper dosnt just disconnect one lead from the battery but also shortens the now powerless flash chip*, thats why it isnt just a jumper you remove but a jumper you move. In the case where the chip is shorted the computer wont boot with the jumper in the wrong position while in the case where the battery is just disconnected the computer will boot with the jumper in clear position.

In no case should powering on the computer with the jumper in clear mode damage the system if the designer of the motherboard wasnt sniffing too much glue during the design! 😁

When it comes to boards which dosnt short the flash chip with the jumper and the flash chip dosnt clear fast enough for my liking I use a screwdriver or the battery it self to short the battery terminals, booting the system while shorting the battery leads and still having the clear BIOS jumper in the normal position could very well kill the motherboard I guess but leaving the AC power on normally dosnt as I have forgotten to turn the PSUs AC switch of more than once.

(Just to clearify flash chip in this case is a simplification for where the volatile BIOS settings are stored which obviously isnt in flash as they are volatile .)