Why all-in-one motherboards are troublesome?

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Why all-in-one motherboards are troublesome?

Postby atang1 » Wed Aug 28, 2002 9:59 am

As technology progress, integrated motherboards are becoming very popular. The cost of computers are coming down to earth. Submicron lithography enable millions of transistors crowded on one small chip. Cost of each transistor is infinitesimoly small. So, integration of video, sound, lan, and modem became a reality.

4 layer pcboards made integrated design a snap. But bending the motherboard in any form of shape became fatal mistakes. You can no longer install the motherboard into the computer case first and take your chances. You have to install the cpu with the huge fan/heatsink on first. Then the sdram or DDR memories because the sockets are easily bend out of shape. Any cables, adaptors, and jumpers had to be connected to the motherboard and check out the fit and correctness of their orientation.

If you are like myself, you would check out and test the motherboard on a bench before you install it in the computer case. Of course, you have to use a telephone book under the motherboard so that the cards or adaptors will have clearance off the bench.

Before you install the operating system into your hard disk, you have to check for the lastest bios update. So that you can use the latest cpu of your choice. Hopefully, your PNP bios will install each driver in the correct sequence, so that the all in one integrated motherboard will have each function working transparently with all the video, sound, lan and modem. If not, you are not ready to install the system into the computer case yet. You have to work out any IRQ conflicts.

Lastly, you have to make sure that you don't tighten the screws holding the motherboard to the computer case too tightly. That is the usual reason for the short life of integrated all in one motherboards. The other one major reason is the over heating of the chipset, or changing cards or memory in the computer case. Good Luck, you will need it.
atang1
 

Postby atang1 » Thu Aug 29, 2002 4:00 pm

Why ATX motherboards have more failures than AT motherboards?

In the days of the AT motherboards, the sockets and the keyboard and mouse connectors were all having masses which are not gigantic and definitely not skyscappers. Now the ATX motherboards at the rear end has super structures of connectors. The masses are so large that they cool down the wave soldering machine(quality control people would insist on insulating the super structure to minimize the heat loss from the wave soldering machine). The motherboard pcboards are nolonger flat. The motherboards are distorted. Distortion is 99% of the failure of pcboards.

The distortion in the planarism is the cause for failures. If you understand how pcboards are made.

Pcboards are made of layers of thin fiberglass and copper foil. The vias or holes are drilled for registration. Then the copper foils are etched to the circuits designed. Then the 4 layers are glued together, using the vias(holes) to line up for 4 layers to be electrically connected thru the vias.. It is done by first plating the inside of those holes, which connects all the four layers of copper foils. Then the vias are filled with solder to give them some strength against shear. If you bend the motherboard, the 4 layers of fiberglass will shear against each other. Then the copper foils will no longer be connecting together. And the motherboard will no longer work. The circuits were broken at the vias. If you knew which vias to be repaired by soldering again, you might be able to fix thoae motherboards.

When you sight at the end along the edge, you can see that the motherboards are not flat. So when you tighten the screws on the computer case. the ATX motherboard will be bent by the screws to be flat as the computer case. Along came vibration and heat expansion, the integrated motherboards will fail fairly soon.

We should never tighten the screws on the ATX motherboard to the case. We should allow for heat and expansion almost like railroad tracks. Then we will also allow for vibration of the whole motherboard, not just the ends away from the screws. We have to baby those ATX motherboards to make them last for at least five years. Circuits with sockets last five years, circuits soldered lasts more than 10 years. Plastic standoffs are the way to go.
atang1
 

Postby lil boi phreak » Thu Aug 29, 2002 4:23 pm

i hope to god im not using this same machine in 5 years. :wink:
Hey, if you want me to take a dump in a box and mark it guaranteed, I will. I got spare time.
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Postby len444 » Thu Aug 29, 2002 8:32 pm

We should never tighten the screws on the ATX motherboard to the case


grounding for esd through the screw posts? tighten one corner and w/ the rest use a nylon or delrin, or even teflon (or combo w/ teflon) washer under the head, just lightly snug, and be certain to use "locktight" on the threads of the screws. next thing to consider is to use gasket material to insulate case fans (reduce noise and vibration- then balancing all fans for vibration reduction?). to what is a mb attatched, al, steel (tin), or other, and it's coefficient of expansion (closest to the mb is best)? cooling on one side of the mb, and not much on the other causing bowing/ cupping- convex to the hotter side.
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Postby atang1 » Fri Aug 30, 2002 7:18 am

Quality means long life, and long life means long warranty. My 1998 computers are still doing their jobs after K6-2(k6-2+ availability may extend their life even more) and other upgrades; even though I changed sdram in the computer case and the dimm sockets are not working good anymore.

Most of the screw problem seems to come with the cheap computer cases. they sell around $18.00 because of too many returns. I had to use only one screw on each motherboard just to keep it in its place. Works fine after that. Grounding is not done at the computer case or the motherboard; it is done from the power supply at the 110AC ground on the wall plug. Too many ground returns give you big 60-120 hz hum problem.

The discussions of all that technical aspect is for many computer buffs who do their own assemblies to appreciate technical support. It does smooth out the little problems and assembly will be a lot more fun.

If you ever go to Compusa and test their latest fastest computers, you will notice that your own 1998 computers are not all that slow. The 2.4 ghz computers are slower than the 1.8 ghz ones, etc. The software is longer and takes longer time to load. And the integrated chipset robs the cpu of much of its speed. What's going on, man?
atang1
 

Postby atang1 » Fri Sep 06, 2002 5:39 pm

A bent motherboard, where the layers of copper foil got disconnected will exhibit strange behavior. Some the video is displaying strange characters. Some the video cards are not recognized. Some memories are not recognized. Some ide connector is not recognized. Some floppy is not recognized. Some no sound.

The fault is really always the same. It is like some wires are broken. Some times bending it backwards and luckily the foils connected again, and the motherboard will work fine. As long as you don;t disturb it again. Some got lucky and used the card board trick to support the bent motherboard. In fact push it up to straighten the motherboard out to reconnect the traces of each layer of copper foil.

In general visual inspection along the edge and sight the motherboard straightness is the first order of the day. Then it has to be bench tested. and all the components will need to be checked before you install them in to the computer case.

And never screw the motherboard down too tight.
atang1
 

Postby atang1 » Sat Sep 14, 2002 5:51 am

The troublesomeness is not limited to broken traces when you bend the motherboard.

Fortunately, some all-in-one motherboards has jumpers or in the bios selections to defeat some of the features of all-in-one. So, some broken features can be replaced by cards if you have more than two slots.

If you don't plan on the sequence of adding functions to the all-in-one motherboards, you may have many conflicts in IRQ assignments. Modem gets IRQ 10; but sound doesn't always get IRQ 5, which is required for legacy compatibility. Then each additional functions are added on in sequence IRQ 11, 12, etc. If you have conflicts due to the automation in Microsoft's operating system, Then you may have to jumper off all of them and jumper on one at a time, so the operating system can recognize each in turn and assign the next IRQ. No more conflict after that.

Having fun? You bet. The more automation, the more preplanning is necessary. All-in-one motherboards, especially.
atang1
 

Postby evasive » Tue Sep 17, 2002 2:05 pm

Disabling all onboard by jumper then enabling one-by-one, like the old days: pulling/adding cards. Neat trick, have to remember that one 8)
We hate rut, but we fear change.
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System error, strike any user to continue...
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Postby atang1 » Wed Sep 18, 2002 4:26 am

Thank you, I have wasted too much time in Microsoft HELP, online support in WinME operating system.
atang1
 

Postby atang1 » Sun Oct 20, 2002 12:58 am

In the early days, motherboards of limited integration has backup AGP and PCI slots so that you can replace the functions with newer cards. These motherboard tend to be very large and very sturdy.

The Matx and baby AT all-in-one motherboards are designed for low cost no fuss throw away concept. They have very few slots. So what do you do when some functions fail or became obsolete? Not much you can do.

Never bend your motherboard, never screw the motherboard too tight on the computer case. Look at the motherboard, visually inspect how flat the motherboard is? They are never flat at all.

Common failures are capacitors dried up. Cmos transistors got moisture contamination and drain the battery down. These failures can be recovered by use, even if at first the motherboard seems dead.

Even if cpu overheats, can be low temperature annealed by just stay in the bios and watch the clock tick after you set it, for a day or two. This is a minimum usage of cpu, but allowing the chip to equalized in temperature distribution and be annealed off all mechanical stresses. The video display uses the cpu, memory and video functions while the bios post code stopped at the display.

But if chipset overheated and failed, the motherboard is officially dead.

Buy yourself a mini post card, and it will show "88". No beeps and no video. If the chipset is cold, it is dead. If the chipset is warm, you might take a chance, remove all the cpu, etc just cook the motherboard for a day or two to cure the capacitors, then drive off the moisture in the ICs for two weeks. Good luck, but what have you got to lose? Except perhaps a dead motherboard comes alive again.
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