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New RAM issues...

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Raddit123

Experienced Member
Joined
Feb 14, 2015
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108
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Hi all,

so I've just bought a 586 PC of eBay, and having repaired the RTC I'm now trying to upgrade the RAM. It has 6 ram sockets, four fit this sort of RAM:

image.jpg

And two, this kind:

image.jpg

So there where four modules of the first kind installed, totalling 48MB. I removed these and installed two of the second kind which should total 128MB. Upon turning the system on, all the lights and fans come on and a rather loud continuous beep is played, coupled with no system activity. I've tried each of the larger modules separately too no avail, any ideas?
 
The second kind is SDRAM. I'm guessing you took out single sided RAM and have replaced it with some double sided RAM?

Some motherboards can be picky about single vs double sided. It's also possible you have bought some dead RAM. My money is on the former; the SDRAM you have tried to install isn't compatible with the motherboard.

EDIT: Have you got a manual for the motherboard (or can google for one)? That will tell you what types of RAM it supports.
 
The old ram was double sided, the new stuff is single, I've got a double sided module knocking around somewhere. Most of this stuff came from some of my dad's office computers in about 2004, it worked then but has been stored in all sorts of places since....

I'll try the other module, but I think it's going to be something like 256MB, which will be too big I'm guessing. The computer and motherboard are completely unbranded, so I have no idea who it's by. The BIOS code doesn't match to any manufacturer either, having been throughout list of 300 or so that used this BIOS.
 
IIRC there were EDO RAM modules in a SDRAM form factor, and depending on the makers of both the modules and the sockets, you could sometimes get regular SDRAM to plug in, even though that's not what it was designed for. I wouldn't be surprised to see something like that on a Pentium board with a SDRAM-looking slot.
 
glitch said:
IIRC there were EDO RAM modules in a SDRAM form factor, and depending on the makers of both the modules and the sockets, you could sometimes get regular SDRAM to plug in, even though that's not what it was designed for. I wouldn't be surprised to see something like that on a Pentium board with a SDRAM-looking slot.
Click to expand...
Mostek-style (aka "FPM/EDO") DRAM in 168-pin DIMMs came first, then SDRAM decided to use the same 168-pin DIMM package. The first photo looks like SOJ chips which are Mostek-style DRAM. The second picture looks like TSOP chips which maybe either Mostek-style DRAM or SDRAM, but most likely in this case SDRAM. Which chipset is the board using?
 
Memories of the top photo (SIMM 72 pins) are placed in pairs, and the lower (DIMM) can be set individually. The Pentium motherboards (that is what you got) support DIMMs of 3.3 and 5 V, and bring 2 jumpers to change the voltage. Usually only support memory DIMMs up to 32 Mb with chips on both sides for each socket.

In these motherboards the SIMM memories are placed in pairs and must be the same size, and if possible with the same characteristics. In addition, is not usually possible to use 6 memory banks at once. Normally at most can be used 5, 4 SIMM and one DIMM.
 
On the 168-pin DIMMs the center key defines the voltage (center for 3.3, left side for 5V). JEDEC 21C is contradictory on the left key and the industry arrived at it's own conformity: right for EEPROM based SPD (nearly all buffered/registered and unbuffered SDRAM) and center for hard pin strapping (nearly all async DRAM - EDO and FPM). So you generally can't install the wrong base type of memory because of the physical keying on the socket.
 
Early users of DIMM DRAM (around the P1) era can be pretty finicky. I've got a couple of Amptron P1 boards wtih both 168 pin and 72 pin DRAM sockets. The best that they can recognize is a single 64MB DIMM.
 
eeguru said:
On the 168-pin DIMMs the center key defines the voltage (center for 3.3, left side for 5V). JEDEC 21C is contradictory on the left key and the industry arrived at it's own conformity: right for EEPROM based SPD (nearly all buffered/registered and unbuffered SDRAM) and center for hard pin strapping (nearly all async DRAM - EDO and FPM). So you generally can't install the wrong base type of memory because of the physical keying on the socket.
Click to expand...

Look at the picture the two jumpers at the end of DIMM memory sockets. This allows you to choose the memory voltage. These motherboards had sockets that allowed the installation of both types of memory DIMM http://www.amoretro.de/wp-content/uploads/pc-chips_m537_dma_5.2_socket_7_motherboard_via_vpx_chipset_vx_pro.jpg
 
eeguru said:
I'm not sure if your photo is representative of the OP's motherboard, however the one in your photo does not. I clearly has a center key pin in the middle preventing modules designed for 5V operation to be inserted into the socket.
Click to expand...

This is the motherboard manual shown in the picture. That clarifies that these jumpers are for the voltage of the memory module. http://www.motherboards.org/files/manuals/89/m537v52.pdf

What you mentioned is true but these motherboards was possible to install modules 5v or 3.3v only by changing the voltage of the socket, since the key pin in the socket is thinner than the standard.
 
I have a very vague memory of someone telling me that simultaneously using SIMMs and DIMMs on some motherboards would slowly kill the DIMMs. Now I'm thinking that the culprit must have been a misconfigured motherboard (as discussed above)? Or is there any truth in this? This was way back in the early DIMM era (obviously).
 
I confess confusion. I see discussion about jumpers and such about various motherboards, which is interesting, but what does this have to do with the as-yet-indentified OP's motherboard? Do we have people who practice divination in their spare time?
 
There are any number of areas in which a DIMM that physically fits may still be incompatible. One of my favorites is byte-vs.-word oriented ECC. The best you can do is know that because the voltage key is reliable, you're unlikely to physically destroy anything.
 
Chuck(G) said:
I confess confusion. I see discussion about jumpers and such about various motherboards, which is interesting, but what does this have to do with the as-yet-indentified OP's motherboard? Do we have people who practice divination in their spare time?
Click to expand...

It's called topic drift, Chuck. Eventually we'll get back to the OP. Meanwhile, try to keep up! ;)
 
Last edited:
Krille said:
It's called topic drift, Chuck. Eventually we'll get back to the OP. Meanwhile, try to keep up! ;)
Click to expand...

Yeah, it's getting worse as I get older, particularly when I'm listening to my wife. Every once in awhile (more frequently as I age), I scratch my head and look up and say"Context?".

Okay, I'll try to follow along.
 
Krille said:
I have a very vague memory of someone telling me that simultaneously using SIMMs and DIMMs on some motherboards would slowly kill the DIMMs.
Click to expand...
The problem is I think mixing 5v and 3.3v (including SDRAM) DRAM on the same mobo, which is of course not a good idea (though 16MBit SDRAM would tolerate this more than later SDRAM chips). For fun, there is a reliability report on a more modern SDRAM chip publicly available now: http://www.alliancememory.com/pdf/d...- Micron QualReliability report _y27b_mjp.pdf
 
Krille said:
I have a very vague memory of someone telling me that simultaneously using SIMMs and DIMMs on some motherboards would slowly kill the DIMMs. Now I'm thinking that the culprit must have been a misconfigured motherboard (as discussed above)? Or is there any truth in this? This was way back in the early DIMM era (obviously).
Click to expand...

I guess this would depend on if the motherboard had two voltage planes (one for each type of memory) or if it had a single voltage regulator that switched depending on what type of memory was detected. The easiest way to figure this out would just be to probe the VCC pins on the slots with both memory modules installed and see what you find.

Though I don't ever recall one of those dual memory type boards even working properly with both types of memory installed. It would either not POST at all, or it would ignore one of the sets of memory like it didn't exist.
 
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