# Only 2 out of 4 ram slots are working.



## Mishque (Aug 19, 2011)

Hi everyone. 
I'm having a problem with my ram.
Earlier today i was running on 3 Gig ddr2 ram using slots 1,2 and 3. (1gb per stick)
I had another 1gb ddr2 stick that i wanted to add. When i was done, the pc would not boot up. Fans were running, but no post or beeps, just a black screen. After messing with it a while, i found out that if i inserted ram into slot 1 or 3, or both at the same time, the pc would boot. But when i tried 2 or 4, it would not. I tried all the sticks on 1 and 3 and it worked fine, so i know it's not the ram. Also i saw a thread about bent cpu pins causing this problem. I tried 3 different cpu's, still having the problem. I tried another psu, didn't work. Tried resetting cmos, didn't work. I am 100% sure that the ram is compatible with the motherboard. I have an Asus M4A77. I tried cleaning the slots, and the ram. Still nothing. The ram voltage is okay, since i was using the ram, and then it suddently stopped working when i added 1 more stick.

I tried pulling the pc apart and then reassembling it. Problem persists.
I'm out of ideas.
Any help is greatly appricieated


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## Wrench97 (May 10, 2008)

Intel, AMD?
Brand and Model of the PC?
If Custom built Brand and model of the mother board and CPU.

Not all boards will boot on the second channel.

Lastly brand and part number of all the ram involved mixing brands and spec is not advisable.


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## Mishque (Aug 19, 2011)

Custom Build

CPU: Amd Athlon II x4 2.8Ghz AM3
Mobo: Asus M4A77
I don't know the brand name of my ram. All it says is 2Rx8 PC2-6400U-666.
All ram is the same brand, same speed, same size.


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## zraupp10 (Mar 2, 2009)

Mishque said:


> I don't know the brand name of my ram. All it says is 2Rx8 PC2-6400U-666.


666? never heard of it, DDr2 is 577; 667; 800; 1066 (there are others)



Mishque said:


> All ram is the same brand, same speed, same size.


How you know you just said


Mishque said:


> I don't know the brand name of my ram


.


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## Wrench97 (May 10, 2008)

PC2-6400 is DDR2 800, 666 is the timings.

The two blue slots are Are channels A1 and B1 , the black Are A2 and B2.

If it works with sticks installed in A1 and B1 then both channels are working.

Use CPUz on the memory tab see if it lists the Brand and part number.


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## Mishque (Aug 19, 2011)

zraupp10 said:


> 666? never heard of it, DDr2 is 577; 667; 800; 1066 (there are others)
> 
> 
> 
> How you know you just said .


All my ram is exactly alike, same labels on it and same speed and size. But i don't see the brand name on the labels.


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## Mishque (Aug 19, 2011)

wrench97 said:


> PC2-6400 is DDR2 800, 666 is the timings.
> 
> The two blue slots are Are channels A1 and B1 , the black Are A2 and B2.
> 
> ...


Yup, it did. '

Brand name: Qimonda
Part number: 64T128020EU2.5B2


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## Wrench97 (May 10, 2008)

What happens if you use slots 1, 2 and 4


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## Mishque (Aug 19, 2011)

Black screen, no post, no beeps. It only works when i use 1 or 3 or both. But if i combine them with anything else then it won't boot.


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## Wrench97 (May 10, 2008)

You started with 1,2 and 3 correct?
Now it won't use 1 and 2 or it works with 1, 2, & 3?


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## Mishque (Aug 19, 2011)

I had 1,2,3 in use, then i added a fourth stick. And now it will only work on slots 1 and 3.
If i for example put ram on slot 1 and 2, pc will not boot. But if i remove ram from slot 2, it will boot up fine. So the only combination i can use is 1 and 3, anything other than that, pc won't boot.


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## Wrench97 (May 10, 2008)

When you had it apart did you remove the CPU and check the pins?

Check the motherboard around the ram slots for burnt traces.


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## Mishque (Aug 19, 2011)

As i said, i tried 3 different cpus, all working. No bent pins. No burnt traces on the mobo.


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## Wrench97 (May 10, 2008)

If it happened across 3 CPU's then it a motherboard problem, is there warranty left on it?


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## Mishque (Aug 19, 2011)

Should be, i bought it 8 months ago.


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## Wrench97 (May 10, 2008)

Time to fill out the RMA request.


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## Mishque (Aug 19, 2011)

Will do, thanx for your help.


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## Wrench97 (May 10, 2008)

Let us know how it goes.


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