Installing Ram problems

[Whiplash]

Alright, i have an older computer and i tried to install some SDRAM into it. Fortunatly there were DIMM modules so one would assume that everything would be fine. Unfortunatly, that wasn't the case. It seemed that the clips that hold in the ram wanted to clip into the wrong place, the holes for the clips were situated much further up. I assumed that this was simply a physical incompatability, and proceeded to remove the clips and insert the RAM none the less. This proved fruitless, the computer didn't hang up or explode in a shower of flames, it simply didn't see the ram at all. I've lloked in at a few sites but haven't been able to find an explanation. So please, if you could tell me whats going on i'd really appreciate it, because, as far as i know, the RAM should be compatible.

Thanks
Whiplash

[snowmonkey]

provid the made and modle of the mobo, may be we could dig out something for you...


cheers

[Whiplash]

Please accept my apologies for taking so long to check up on my topic, i guess the time just got away from me.

It's a PENTIUM MMX 166. It actually says on the pamphlet that it "Features SDRAM Modules", it also says "Fully Compatible with Intel MMX Technology with VXpro+ Chipset" if that makes any difference.

Thanks for responding
Whiplash

[Matt A.]

Make sure you are inserting the DIMMS according to their proper allignment. With the no. 1 pin on the DIMM to the no. 1 pin on the DIMM slot. It should be printed on the mobo at one end of the DIMM slot. Also be sure you are installing the correct DIMM for the mobo. Depending on the voltage requirements of the DIMM the location of a key slot will be slightly different then a DIMM requiring 3.0v instead of 3.3 volts. The difference is only a millimeter or two depending on the DIMM. So it maybe you have a DIMM not meant for your mobo.
Sometimes the DIMM is the correct type but happens to be a very tight fit. I've even had DIMMS where I actually had to file the key slots for the retaining clips slightly before they would fit properly. However, I don't recommend doing this unless you know for sure the DIMM is the correct voltage and type for your mobo and that you don't mind having to toss in the trash incase you mess up and filed something you shouldn't have filed or slipped and scratched a trace on the DIMM card.

[Whiplash]

Thanks for the reply.

I've definetly got the right pins in the right place, and after removing the clips i had inserted the ram anyhow, and like i said, got no response from the computer. This leads me to assume that the RAM is of an incorrect voltage. Where does one find out what kind of voltage RAM is needed, and is it possible that no RAM produced currently will fit into my computer?

Whiplash

[Matt A.]

Well, that depends upon the manufacturer and model of your mobo. Also, if you know who manufacture of the mobo (not just the chipset but the board itself) you can often download the owners manual from their website. In the owners manual it should list what type of ram your mobo uses as well as the specific specifications of the type of ram it uses. If you have one of the older DIMMS still around you can compare it with the DIMMS your trying to install. Look for a two key slots located on the edge of the DIMM that is inserted into the DIMM slot of the mobo. One slot is the DRAM key slot and it's position prevents the wrong type of ram from being inserted. Depending on if the ram is RFU/Buffered/ or Unbuffered DIMM. The other key slot located more towards the center of the DIMM, prevents the wrong type of DIMM from being inserted if it is the incorrect voltage. If the DIMMS are the same type voltage wise the key slots with match perfectly. You'll have to measure very precisely as the difference in measurements is only about 1/16 of an inch or about 2 mm. The key slot for voltage will be centered having the exact same spacing on each side between the DIMM contact pins IF THE DIMM USES 3.3 VOLTS and slightly shifted left of center between the contact pins if it is a 5.0 volt DIMM. That is if holding the DIMM and the DRAM key slot is on the left side. To determine which slot is which hold the DIMM so that you count (going left to right) 20 pins/DRAM KEY SLOT/60 pins/Voltage KEY SLOT/88 pins. Hope this helps.