820-3302 - PRAM reset causes 3 RAM beeps

Sykulski

Member
Hi.

This is an iMac 21-inch (slim version).

Came in with the 3 RAM beep issue. Replaced RAM still beeping three times. Checked DDR PWR 1.5V and 0.75V OK.

Then i replaced the CPU. Now it starts but if I make PRAM reset the 3 beeps return. If I then take out power cord for a while and put it back again it starts normally but the 3 RAM beeps return after each time I PRAM reset.

I then tried putting the original CPU back in. With this CPU it cannot even start. It is beeping three times from beginning.

Any clues?
 

dukefawks

Administrator
Are you using the correct CPU and are you using DDR3L memory 1.35V? I suspect you are using regular DDR3 and not DDR3L
 

Sykulski

Member
Yes i was using "Crucial Mac compatible DDR3L" modules. The same type I always use when making RAM upgrades to these models. The "working" CPU is from an exact same model where it is known to be working.

But the problem is with the board itself because I have now also tried to put the customers "not working" CPU and "not working" RAM into another board and here it is working.

The weird thing is that with customers CPU in customers board it will not even start once but with my CPU in customers board it starts and works until i make the PRAM reset.
 

Sykulski

Member
Yeah. I was thinking the same thing. I have inspected it from the top and all pins are good. But maybe under the socket could be an issue. The history for this machine is that is has been working without any issues for several years but after the customer gave it to his son and the son started to play games almost non-stop for a week or so and then it started to beep. Hmmm... Also it is running fine here all day long without any issues until i make the PRAM reset. I am stumped!
 

Sykulski

Member
Yes. There are only two slots in these models. Same issue if I use only one RAM module in each of the slots.
 
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