RAM upgrade - imac will not boot

[jrockmd]

Running an imac 7,1 aluminum 2GHz core duo. Originally had 1GB ram.

Added a PC2 5300 DDR2 667MHz 1GB Kingston RAM module to the free slot so I could run El Capitan.

The machine was working OK at first, not snappy quick but running, and after a short while started running very slow, choppy, freezing up, basically was non-functional.

So, I thought I'd try more RAM. The machine has 2 slots. I purchased 2x2GB RAM sticks of the above configuration.

If I place both new chips, the machine will not boot, no chimes, I hear the first mechanical sounds of a boot but then nothing.

If I replace the original 1GB ram stick in one slot and one new 2GB stick in the other, it works fine. Actually running faster than before, showing 3GB of RAM functioning.

I would very much like to have all 4GB of RAM but without the factory installed chip in place I can't get it to boot up.

After extensive searching I have found others with this problem but no good solution offered. The chips are 100% seated correctly, both slots are working. I have tried each of the 2GB sticks and they both work when paired with the factory stick, but not when paired with eachother.

Any thoughts?

 

[eric89074]

You're sure both of the 2GB sticks are PC 5300? I've only encountered your scenario when putting in two sticks of RAM that are rated at a higher speed than the one from the factory. However you should hear the loud beeping sound if that's the case.

 

[definitive]

you'll probably have to run some diagnostics on those new memory sticks like http://www.memtest86.com/

sounds like either those sticks might be bad or incompatible. what brand were they? crucial and corsair are usually best third party ram to buy for a mac.

 

[jrockmd]

you'll probably have to run some diagnostics on those new memory sticks like http://www.memtest86.com/

sounds like either those sticks might be bad or incompatible. what brand were they? crucial and corsair are usually best third party ram to buy for a mac.

Thanks for your reply! They are Kingston brand. They both work when paired with the factory RAM so they both work. This seems like it rules out a bad module or incompatibility. I'll check out the link and update the thread if I find anything...
[doublepost=1467087884][/doublepost]

You're sure both of the 2GB sticks are PC 5300? I've only encountered your scenario when putting in two sticks of RAM that are rated at a higher speed than the one from the factory. However you should hear the loud beeping sound if that's the case.

Yep I am certain they are both identical and meet the specs for this model imac (specs noted in original post)

 

[maflynn]

Pull both new ram modules out, and then place one in the computer and try to boot, if it works, swap it out and see if the other doesn't boot. You bought new ram, and at least one module is defective, once you isolate which one contact the retailer from where you got it.

 

[akash.nu]

From what the OP has mentioned so far, it could be that the new RAM sticks may be fine, but are you sure your motherboard is able to handle 4GB altogether? Just a thought.

Update - never mind, just checked. It should support 4GB as long as you've bought the correct type.

 

[jrockmd]

Pull both new ram modules out, and then place one in the computer and try to boot, if it works, swap it out and see if the other doesn't boot. You bought new ram, and at least one module is defective, once you isolate which one contact the retailer from where you got it.

Thanks, I will try that, although both RAM sticks work when each is paired with the factory stick. I haven't tried them solo yet...