DIY PC case

[Richard]

If there is any hint of stressing the board when tightening it down then I would prefer the use of rubber grommets to avoid stress while still holding it securely in place. However, do remember that stress can be accumulative, every future incident adding to past history until the failure become permanent. That said I still favour the idea of a badly seated part that is very slightly moving out of position. While the machine is working try a memory testing programme and see if it reports any hint of an issue.

Both the semi spring-loaded contacts and the tracks on PCBs can very easily become deranged by unwanted movements so such pulls are best avoided, even poor soldering can become an issue when the tension pulls just a bit in an undesirable direction.

[tadka]

Who knows. It is working now. Once the fibre washers arrived I’ll try again. I read online that motherboard screws’ head should not be wider than a certain size. These washers definitely are wider. At the moment I’m hoping that’s the case and the fibre washers will solve the problem. I really don’t want to spend days trying to figure this out. I’m getting too old for this  😛

[Ed P]

Not your problem I know, but I once had a mobo that was mounted on a two part tray and the trays in turn were mounted in the pc case. Unless I carefully torqued up all the mounting screws I would be guaranteed to get failures. To this day I’m not sure what caused the failures — earth loops were in vogue but I suspect it was the bad connections as referred to by Richard.

[tadka]

I do struggle with the concept of it having problems due to being not perfectly straight. It gets bent quite a lot each time I am removing it or fitting it back in a case. It flexes every time I handle it. But it works fine after. I think there got to be another explanation. But then I’ve been proven wrong many a time when I thought something just can’t be.

[Les.]

As I said in a previous reply, the way the mother board is fastened down DOES matter. Various “different” fixing screws were supplied by different mother board suppliers, but they all had the same base size, sometimes looking like a built in washer.

We used to build PCs (Yours truly built well over 1,000) but we also used to sell components. I had very few component failures, but at least 30% of the “builds” supplied as components would bring complaints of (typically) faulty mother board. Instead of matching mounting holes for M/Bs, and fitting support pillars there, every threaded hole would get a pillar. Faulty M/B. I would always show exactly what they had done. Sometimes, with the offending pillar removed, the M/B was still OK.

Then there were the “This mother board is faulty” cases which I would “cure” by setting the bios correctly. Of course, often they did kill the M/B, but 9 times out of 10, the Boss would return it to gigabyte or whoever. Why he continued to supply to such customers I really don’t know. The way we priced stuff, it cost about the same if I built it, with no comebacks.

But back to motherboards. There was a time when electronics involved point to point wiring of everything. (1930’s radios) but tagboards were quickly invented saving time. Then in the ’50s, we had printed circuits with copper deposited on one side. Later, PCBs came with print on BOTH sides, and together with machine insertion of components, more improvements and time saving. Today, component boards (I will refrain from the term PCBs now) copper was deposited on numerous layers. Such are today’s computer mother boards.

Now quietly think about the result of distortion. An open circuit three layers down maybe.

All your mounting pillars, or whatever substitute is used, need to be the same height. Only fit screws and pillars where the hole has an obvious ring of print on both sides, and ensure the mounting screw (and pillars) do not exceed the diameter of that ring of tinned copper print around the hole.

Les, who was playing with things electrical over 70 years ago, and ever since.

[Richard]

Les, though I never had a motherboard failure that was a darned good explanation of the mechanism of potential failure and how boards are now constructed. Any stress at any point that pulls or distorts the board has the potential to do damages, though in this case I suspect that it is possibly where an item, e.g. memory or the like has to be inserted into its connection ‘home’, with the CPU running a close second in the probability stakes, though to be honest it still could be anything. Since it is OK ‘unmounted’ I think earths maybe get ruled out, however, all the other ‘runners’ are clearly still in the race. I know how it feels to get tired before a project is done, (most times I feel like that before I start these days), but there is some mistake that is causing the issues, and it needs to be found to cause sleep to become restful once more.

[Bob Williams]

Ed, I had a mobo similar to that many builds ago, when I was building desktops as a sideline from printing. I installed and removed the thing 3 times and it still would not work. Then I ran the board on the desk sans case and it worked. So I gave up installing the mobo in the case, fitted it to the trays and fitted the trays to the desktop case. I still don’t know why it worked, but accepted that it did and passed it to the customer. AFAIK it may still be working, at least I never had a comeback. IIRC it was an ASrock.

Les I once rescued a board for a guy who had completely messed up his own build by cross-threading the standoffs. How he did that, he could not explain, but I first told him to RMA the parts in the hope that he could exchange them. He didn’t think they would and I guess he was right, so I told him I would give it some thought, with absolutely no guarantees. I found some captive nuts and standoffs to fit in my “Bitsa” box, managed to get them together and installed the mobo to this jury-rigged setup. To my amazement relief, it all worked and he went away happy. I no longer live near the guy, which is perhaps a good thing.??

After many years of repairing and building, with a few complete strips of older, knackered machines, I have a box full of many different standoffs, screws, brackets, doobries, wotsits and probably some bits which are now nameless. Every now and again, some of this stuff finds itself a purpose in life. My SWMBO wanted me to get rid a while ago and was told she could only remove them from my cold, dead hands. I have WEEE’d quite enough stuff for now.

When the Thought Police arrive at your door, think -
I'm out.

[tadka]

Looks like I have to eat my hat.

I added the fibre washers on both sides of the motherboard and tightened it just as hard as last time. After all I didn’t think pressure was the problem here.

So, I tightened the #1 nuts. Then I tightened the #2 nuts. Only this time I added a metal washer between them to help me tighten #2 against #1. I connected the PSU with the motherboard flat on the ground and it worked, fans were spinning.

Then, while holding the plywood board flat on my lap I lowered the motherboard onto it. The screws slid in easily, there is no stress anywhere (though I have to say the motherboard itself is quite warped around the CPU area and because of that two of the corner screws were slightly up “in the air”, the nuts weren’t resting on the board, but hardly any pressure at all is required to push them against the board).

So, the board is in, it’s flat on my lap and I finger-tighten the #3 nuts on the back of the board. Then I put it in a vertical position and torque the #3 nuts with a spanner (small 7mm thing) a bit tighter. And then I add #4 nuts and tighten them against the #3 nuts to make sure they all stay in place. I then connect the PSU and… nothing. LEDs are lit but not even a twitch from the fans.

I undo the back nuts (#4&3) a little. Press the power button and the fans are spinning! It baffles me how it made the difference but it did.

I now put everything together (I mean everything fully assembled). The PC is dead…

It took some fiddling with it to finally get it working.

I think the WiFi card might have been being pressed too hard against its slot, so I bent the end of its bracket so the front of the case is not pushing on it. Then the thick shielded power cable was under stress from the front of the case too as there isn’t much room. I pushed it into a better position. It all looked good and it was working. And then it stopped working again after I torqued the back nuts a bit again. So in the end I did the #3 nuts only finger-tight and the #4 nuts a bit tighter against the #3 nuts.

It’s working now but damn that thing is fussy…

[Richard]

Bob, a while ago I got one of those tidy filing things, shortly after that I stopped build activities. One thing I do remember is that some mounts were plastic with two sprung loaded fingers that closed down when the board slid over them but which sprang out to hold the board firmly but without excess pressure. I am not sure I ever used any  of them, but they sounded like a good idea at the time.

Tadka, when all else fails it has t be the thought that you originally rejected. I am glad it is now working, but I am concerned that you might well have over tightened something, especially given the multi layer nature of many boards.

I did once fault find a system built for a relation by one of his young and aspiring friends. Sadly they had used no stand-offs so as a surprise to no one who knew about such things, it did not work. I rebuilt it, correctly, and as luck would have it the thing worked, but I was surprised to say the least.

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