One RAM slot is not working - only beeping

If the module works in one slot and not the other, the slot is bad -- the mainboard will need replacement.

On a 10 year old system like this one, the system is better replaced than repaired.  The boards appear to be only $100 or so at this point -- but that's still around twice the value of a complete, used working system.

If the system functions otherwise and 8G RAM is OK, you can run up to a single 8G module in the working slot.

In a working socket, that would result in dual channel operation if the modules are the same.

If neither of your current modules work in the second socket, though -- no change;  the socket is the issue - not the modules.

If you have tried two modules that fail to work in that one slot, the slot is faulty.  The mainboard would need to be replaced.

You're likely better off with 8G in one slot than 8+4 anyway, since it nets you the same total  memory running at full bandwidth - -a single 8G will be dual channel.  With 8+4, the same 8 G would be dual channel;  the remaining 4 will be half-bandwidth.

Although the system is working perfectly fine after I have upgraded it with SSD and RAM from 4 to 8GB, I want to add that 4GB RAM stick in the lower RAM-slot to make it 12GB of total RAM.

You mean to say that RAM Board needs to be replaced or whole motherboard needs replacement? any other viable solution?

Got it. And what about If I add another identical 8GB stick?

Welcome to the Dell Community  @AlphaBravo1 

Did you check the socket for any debris?

We have found yellow and/or white labels jammed in the socket.

Next we would use 91% isopropyl alcohol and a toothbrush to clean the socket. 

Electro -Wash is good but I would still use a toothbrush.

After this if it still fails we would mark it "Bad Memory Slot" and sell as is.

Best regards and good luck,

U2

Although I haven't used alcohol yet I have used brush to clean it. There are no obvious debris visible.

What max memory I can use in my laptop?

With two functional slots, 16 G;  at present, your system will be limited to 8.

Some colleague of mine said that I may need identical sized memory modules in both slots for it to boot. Just putting the stick in slot 1 rather than 0 (which works) is not the same. This is because the memory may require dual channel which requires two identical sized memory modules. Motherboards can have these requirements.

Can it be like this? How can I confirm this dear?

@AlphaBravo1 

You need a matching pair for "Dual Memory" or as Dell calls it "Dual Interleave"!!!

They do not need to match to be able to boot!!!!!

Regards,

U2

Sorry I couldn't get you. should I try an identical 8GB RAM stick with the previous one?

Matching modules are not required for powerup.  Install just one module that does work in the other slot, into the suspect slot.  If the system won't POST (power up self test), the slot is bad.