820-3299 - 3 Beeps iMac - RAM Issue?

[mccafe]

Hello guys,

I have an 820-3299 that originally had a question mark issue. We decided to switch out the hard drive with an SSD and when putting it together, it no longer wants to boot and has 3 beeps, few seconds pause, and 3 beeps again until I power it down indicating RAM detected in bay but unable to use it? I've tried known good working RAM and still the same. I completely removed all RAM sticks and it would give me 1 beep indicating no RAM in bay. This SSD upgrade involves removing the board in order to remove the hard drive unfortunately so I am unsure if something had happened during the removal, but I'd like to troubleshoot the logic board and need to know where to start.

Thanks in advance for the help.

 

[2informaticos]

Disconnect all, keep only 12V and speaker connected.
Check if still beeps.

 

[mccafe]

Disconnected everything except 12V, left speaker, CPU, couple RAM sticks and still 3 beeps. I also disconnected RAM sticks and it gives me 1 beep in this case. Put it back, 3 beeps.

PPVDDQ_S3_DDR = 1.5 volts steady
R5260 / R5261 = 3.3 volts for PCH / Memory Channel A & B SMBUS pull-up resistors

On a known working iMac, it looks like PPVDDQ_S3_DDR varies between 1.2 - 1.3 volts. I am guessing its because the RAM is actually being used. When the 3 beeps is happening, I have the two solid diagnostic LEDs on and I believe this indicates all sys power is good?

Could this be related to a corrupted BIOS by any chance?

 

[2informaticos]

You can try BIOS, to discard it.
Don't forget to make backup first.

Did you test with one RAM module at time, on each slot?
Try with PC3 and PC3L too; don't mix them.

 

[mccafe]

I’m going to search for a ROM to rule out the BIOS. Does anyone have a link to a download?

I tried one stick, in each slot - no go. I’ll try with PC3 vs PC3L when I get the chance. Also, tried new CMOS battery.