# 3rd + 4th RAM slots not working



## yosoynoy (Jul 8, 2010)

Greetings,

I've been up and down, through and through looking for a solution to a problem I'm facing with a pc build I started last year and have been upgrading piece by piece ever since. The most recent upgrade on the list was a new OS and an extra 4 gigs (for a total of 4x2gb) of RAM. After installing Windows 7, and getting my new RAM, I installed just three sticks to test a boot. I got to my desktop without any problem. Checking system properties showed that I had my 6 gigs installed and everything seemed OK. I shut down the computer and installed the fourth stick. Nothing. From then on I have never been able to boot with any RAM sticks in the third or fourth slots ever again. In fact, while troubleshooting the issue, my Win7 installation/hard drives managed to get corrupted to the point of needing to reformat.

A few notes:
1. One of each (new and old) RAM in the first and second slot works fine, so this leads me to believe it isn't a compatibility issue.
2. I took out one of my crossfired HD 4870's and still nothing - so I doubt it's a PSU problem.
3. Updating the BIOS did nothing, neither did resetting all clocks and settings to defaults.
4. The fact that I had to reformat everything seems to cancel out any possible existing software incompatibilities.
5. Yes, paired RAM sticks are in the correct color-coded DIMM slots.
6. Asus technical phone support guy claimed it's my CPU that has a bad memory controller. He jumped to this conclusion rather quickly however (within 2 minutes), and from what I've read then none of the slots should be working.
7. Although my newer set of RAM isn't on the QVL, it is working 100% effectively in my computer right now, but only because they are both in the first two DIMM slots.
8. Changing the voltage and timings to the lower RAM's doesn't do anything either. And I'll say it again, even if I use one of each type of RAM it's totally fine as long as it's in the first two slots - even without modifying the BIOS RAM settings. To break it down:

Matched pair of old RAM in first two slots = Fine
Matched pair of new RAM in first two slots = Fine
One of each type RAM in first two slots = Fine
Any time ANY RAM stick is in the 3rd or 4th slot (even if I'm NOT using the first 2 slots) = Can't boot

Let me know if I'm just being stubborn, but I figure if the two different types of RAM can coexist peacefully in the first two slots, that it isn't a RAM compatibility issue. Everything seems to point to faulty DIMM slots, at least to me.

CPU: http://www.newegg.com/Product/Product.aspx?Item=N82E16819103649
MOBO: http://www.newegg.com/Product/Product.aspx?Item=N82E16813131366
RAM pt1: http://www.newegg.com/Product/Product.aspx?Item=N82E16820227297
RAM pt2: http://www.newegg.com/Product/Product.aspx?Item=N82E16820211409

If there's any more information I can give or forgot, please let me know, and thanks a billion for getting this far!


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## speedster123 (Oct 18, 2006)

> I took out one of my crossfired HD 4870's and still nothing - so I doubt it's a PSU problem


what is the supply?


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## Wrench97 (May 10, 2008)

What voltages are you running the ram?
Looks like both sets will support 1.7v Ideally if your using 4 sticks you would want them matched.


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## Tyree (May 10, 2009)

If no RAM will work in slots 3 & 4 (using one stick at a time) then the Mobo slots would appear to be the problem.
Filling all the RAM slots on a Mobo can cause Voltage problems. Mixing RAM brands/specs is never advised and A-Data RAM is known for issues.


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## yosoynoy (Jul 8, 2010)

@ speedster123
This is the PSU: http://www.newegg.com/Product/Product.aspx?Item=N82E16817371015&cm_re=ea650-_-17-371-015-_-Product

@ wrench97
Yes, I've tried 1.7v (amongst a bunch of others), and matched all timings to the lower sticks' values, to no avail.

@ Tyree
This is what I'm figuring. Faulty DIMM slots on the MOBO. I understand the risks of using different makes of RAM, but wouldn't the fact that one of each type works fine in the first two slots rule out compatibility issues? Maybe I'll try to get a different customer service rep on the phone and see what they say.


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## Wrench97 (May 10, 2008)

They can both be compatible with the board but not with each other.


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## yosoynoy (Jul 8, 2010)

Then how am I running one of each brand of stick side by side in the first two slots as I'm typing this?


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## Wrench97 (May 10, 2008)

They obviously don't work when you fill the slots, so you have 3 choices, try matched sticks, replace the motherboard, or run 2 sticks. not sure what you want you hear so believe what you want.


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## nhavistech (Jul 23, 2010)

Sounds like a replacement motherboard (identical model) will show that the old motherboard is faulty.


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