Continuous beeps are memory errors. I don't think you can put a 72pin SIMM the wrong way around, so you can't fry a motherboard that way. However you may have made it fit into the socket the wrong way around forcefully in which case it is more likely that you physically damaged the pins in the socket or the connectors on the SIMMs themselves than damage the motherboard or RAM electically. Take up close and clear photos of the sockets please.

One side of the SIMM module is cut out, I can't imagine how you could fit them in reverse? Try to remove all components again, clean RAM contacts and insert back. Clear the CMOS, set the correct multiplier and FSB for your CPU and turn on the PC.

appiah4 wrote on 2021-06-07, 10:28:

I don't think you can put a 72pin SIMM the wrong way around

When the motherboard wouldn't boot after I had set the cpu speed to 150mhz, I turned off the system, removed and then reseated all the components. I turned the system back on; there was no display and it immediately started producing long continuous beeps. I turned it back off and removed everything again.

I suddenly thought of the RAM, and realized I had probably inserted it backwards. So I inserted one of the RAM modules (only one) in the other direction as opposed to when the system produced those long continuous beeps. So, yes, I inserted at least 1 of the 2 RAM modules backwards into at least 1 of the slots.

appiah4 wrote on 2021-06-07, 10:28:

Take up close and clear photos of the sockets please.

I'm at my job now. I will do so when I get home.

Ydee wrote on 2021-06-07, 10:36:

One side of the SIMM module is cut out, I can't imagine how you could fit them in reverse?

All I can say is that the modules "fit" when I inserted them again after the system wouldn't boot at 150Mhz. It's not like I used a hammer. I applied a moderate amount of force, but it didn't feel excessive.

Ydee wrote on 2021-06-07, 10:36:

Try to remove all components again, clean RAM contacts and insert back. Clear the CMOS, set the correct multiplier and FSB for your CPU and turn on the PC.

Except for cleaning the RAM contacts, I did all of that twice. No result, nothing changed. Nothing but long continuous beeps.

If it "fit" without forcing it can't have been the wrong way around, you probably did not install them properly, ie. they are not making good contact. push them in at an angle until the contacts are all in the socet before angling it forward (or back, depending). Try removing and reinstalling the RAM modules until they work. There may also be some oxidation at work here so you may want to spray some deoxide on the SIMM sockets.

Also, remember that you have to put your RAM into Bank 0. System will not run without a populated Bank 0 (or one that is only partially populated).

appiah4 wrote on 2021-06-07, 12:57:

If it "fit" without forcing it can't have been the wrong way around, you probably did not install them properly, ie. they are not making good contact.

Thanks for the insight, but I am quite sure that I inserted at least 1 module in both directions, i.e. including backwards. Like I said, I didn't think I applied a lot of force on the modules, but maybe I forced them without realizing it?

I'll try again when I get home (in about 3 hours). I will remove all the components from the motherboard again, clean the contacts on the modules with some alcohol, take pictures of both the modules and the slots and reseat everything.

The 72-pin simm module has a cut-out on one side. The module slot has a locking key on the same side to prevent the module from being installed incorrectly. It may be possible to install the module in reverse, but certainly not easily and without the use of light violence. Maybe you really didn't have the modules inserted fully (holes need to land on the pins and lock the sides to snap).

Ydee wrote on 2021-06-07, 13:45:

The 72-pin simm module has a cut-out on one side. The module slot has a locking key on the same side to prevent the module from being installed incorrectly. It may be possible to install the module in reverse, but certainly not easily and without the use of light violence. Maybe you really didn't have the modules inserted fully (holes need to land on the pins and lock the sides to snap).

But what if I inserted 1 or both modules "loosely/halfway" backwards? I'm thinking that may have been what happened. Would the board still have fried (or otherwise killed) itself with a backwards (though not fully inserted) module?

When I get home, I'll do what I listed and I'll get back.

Thanks all for your insight.

EDIT: The system also produced long continuous beeps when I left out the RAM modules. Is that to be expected?

When I tried to put 2GB RAM into my Epox 8K5A2+ motherboard I ended up in situation when nothing worked and there was always a memory error on diagnostic lcd, no matter how many or what memory modules I tried (I have various memory sizes). I thought I cracked the board somewhere, it made no sense. I cleared CMOS and it started to work again.

I made pictures of both the RAM sockets and the modules.

I inserted the modules into the two slots closest to the IDE interface yesterday. I just checked the board's schematics and those slots are Bank 1.

Here are the RAM slots.

I removed all the components again, including the RTC.

I cleaned the contacts of the RAM modules witth alcohol. I then reseated all the components on the board.

This time I put the RAM modules in Bank 0, with the cut-out where the notch is in the slots, to the side next to the two power connectors for the cables with the black wires in the middle.

I turned on the system and it still produced long continuous beeps.

I'm guessing I really did insert the RAM modules backwards (into Bank 1) yesterday. Like I said, I didn't apply a lot of force, but maybe they were in far enough to cause the board to die when I pressed the power button? Is thatpossible?

appiah4 wrote on 2021-06-07, 10:28:

Take up close and clear photos of the sockets please.

What do you think, based on the pictures I posted?

Odiseo wrote on 2021-06-07, 18:09:

I removed all the components again, including the RTC. […]
Show full quote

I removed all the components again, including the RTC.

I cleaned the contacts of the RAM modules witth alcohol. I then reseated all the components on the board.

This time I put the RAM modules in Bank 0, with the cut-out where the notch is in the slots, to the side next to the two power connectors for the cables with the black wires in the middle.

I turned on the system and it still produced long continuous beeps.

I'm guessing I really did insert the RAM modules backwards (into Bank 1) yesterday. Like I said, I didn't apply a lot of force, but maybe they were in far enough to cause the board to die when I pressed the power button? Is thatpossible?

Possible but not likely.

Odiseo wrote on 2021-06-07, 18:09:

appiah4 wrote on 2021-06-07, 10:28:

Take up close and clear photos of the sockets please.

What do you think, based on the pictures I posted?

I can't see physical damage.

Just to be sure we are on the same page, when I say Bank 0 I mean the two slots marked SIMM1 and SIMM2, the two at the top edge of the board. Fill only those two, with identical ram sticks.

appiah4 wrote on 2021-06-07, 20:30:

I can't see physical damage.

That's what I thought too. I had my hopes up when I saw both the modules and the slots looked fine and, later, when I realized I inserted the modules into Bank 1 yesterday.

appiah4 wrote on 2021-06-07, 20:30:

Just to be sure we are on the same page, when I say Bank 0 I mean the two slots marked SIMM1 and SIMM2, the two at the top edge of the board. Fill only those two, with identical ram sticks.

Yes, those are the two slots into which I inserted the modules today. The two slots closest to the side of the board, labeled SIMM1 and SIMM2.

Is there something between the slots 3 & 4, near the top?

snufkin wrote on 2021-06-07, 20:57:

Is there something between the slots 3 & 4, near the top?

I think you're right. I see something too. I'll take the board out of the case again tomorrow to have a closer look.

appiah4 wrote on 2021-06-07, 20:30:

Possible but not likely.

Assuming that I *probably did* insert the modules backwards (albeit loosely) into Bank 1 yesterday without physical damage having resulted from this on the modules nor the slots, Is there still hope for this board? Is there anything else I can do to get it to boot?

Odiseo wrote on 2021-06-07, 21:52:

Assuming that I *probably did* insert the modules backwards (albeit loosely) into Bank 1 yesterday without physical damage having resulted from this on the modules nor the slots, Is there still hope for this board? Is there anything else I can do to get it to boot?

No idea really. If that's happened (and it does seem unlikely without ending up breaking either the simm or the slot) then having +5 applied to non-power pins may have damaged the module (some chips have the max voltage on an input pin as Vdd+a tiny bit, so applying 5V to an input is bad if the actual 5V supply isn't connected).

Let's have a look at the power pins in the pinout. Assuming it was rotated 180 degrees, then:

1Pin MB   RAM  Pin
2 1  GND  GND  72
310  +5   D14  63
414  A2   +5   59
530  +5   CAS1 43
634  RAS2 GND  39
7
839  GND  RAS2 34
943  CAS1 +5   30
1059  +5   A2   14
1163  D14  +5   10
1272  GND  GND   1

So, the RAS2 signal from the motherboard may have been shorted to ground, could damage the chipset output driver? +5V was applied directly to D14, A2 and CAS1 on the modules, with no +5v applied to the module Vdd, could have damaged the module. CAS1, D14 and A2 from the motherboard were probably all shorted together through the 5V connection on the module, could have caused problems for the chipset.

A lot of uncertainty there though. I'd get the board out, check out if there is anything between the slots (it looks to me like it might be a solder splash, but no idea where that'd come from), and check if any of the solder joints between slot and motherboard were damaged if there was a lot of force put on the slot.

snufkin wrote on 2021-06-07, 22:29:

I'd get the board out, check out if there is anything between the slots (it looks to me like it might be a solder splash, but no idea where that'd come from), and check if any of the solder joints between slot and motherboard were damaged if there was a lot of force put on the slot.

Yes, I'll get the board out of the case again tomorrow and check if there is something between slots 3 and 4.

I'm looking to get another Socket 7 motherboard. Any advice? I looked on eBay, but there are many that are untested, even known to be faulty, or very expensive. Any idea where and how to look for a suitable board?

I'm in Belgium. There is nothing on my local auction and second-hand websites.

Some of the boards this seller (edit by Dominus: removed link) offers seem interesting: tested and in working order, reasonably priced and they ship for free to any country.

Did you try different RAM sticks in that board?

It's possible that you fried the sticks you inserted backward and that the board is still fine.