System won´t boot if RAM is installed on Slots 2 and 4

[arajigar]

Hi. As I have initiated here:

http://www.tomshardware.co.uk/answers/id-3702761/system-upgrade-bit-advice-z77-d3h-rev-gigabyte-gtx-1050.html

I have built a new system and...I find myself having some BIG troubles with RAM. The system parts are (if you don´t want to read the other thread):

-MOBO: Gigabyte GA-Z77M-D3H rev 1.0
-Intel Core i5 3550
-SSD Kingston 120 GB
-Gigabyte GTX 1050 2GB OC DDR5
-16 (4x4) GB DDR3 RAM GSkill RipjawsZ 1866 Mhz (from the same pack)
-Nox Hummer PSU 650 W

My problem is as follows:

The MOBO has 4 Slots for RAM Double Channel, 1,2,3 & 4. All of the sticks of RAM work fine if I put them on slots 1 and 3, but If I try to put any more sticks on slot 2 or 4, I do obtain 10 seconds of continuous short beeps until the system reboots on an infinite loop.

-I did try the RAM swapping and they work on Slots 1 and 3 and fails on 2 and 4.
-I did try to re-seat the CPU heatsink (I did read that "memory controller not well sitted" could be the problem).

-Did not try to clear CMOS (yet).
-Did not UPDATE BIOS (yet again).

This RAM has worked on a previous MOBO (they are second hand).
What are the possible causes (and solutions) to this problem?.

 

[DRagor]

First a question: what happens if you put 2 sticks in slots 2 and 4 only?

 

[ko888]

One of the memory channels on the motherboard has failed. Have you checked for any bent/damaged pins in the CPU socket?

 

[Doctor Rob]

Sounds to me like its an issue with the RAM or Motherboard.

You could also make sure the RAM settings in bios are set properly then try the ram again kinda thing... like make sure its set at the proper voltage and such.

 

[Doctor Rob]

ko888 is more likely correct. OR the CPU is not seated properly.. NOT the heatsink. I had this issue with a new Threadripper system I built I had to put it in twice before the ram was fully there kinda thing.

 

[arajigar]

I did not touched the CPU, but I will try to see if some of the CPU pins are damaged.
Aniway, how can I know if a channel is broken?

EDIT: the CPU has no pins, it has little golden tiles. I saw three of them look like dirty. I cleaned it very softly and blowed the socket with air. I'll post the results.

 

[arajigar]

No luck. The system refuses to boot if I try to install one more stick of RAM on slots 2 & 4. I have actually running 8 GB, the BIOS show no info about A channel, is it as if that channel does not exist. RAM is running on single channel and at a frequency of 941 Mhz, just half of what it is supposed to be. I am quite lost.

BTW the channel A seems to be not active in BIOS, but the RAM works on slot 1.

LAST EDIT!!: sorry for being a complete MORON. When Ko888 pointed to defective pins, I thought that those pins were located on the CPU, but stupid me did not realize that the pins were located ON THE SOCKET, and, effectively, there were almost 10 of them bent, like if the people that built the system let something fall on them. In fact, I was curious to see that the slots 1 and 3 were used even if the right setup was 1 and 2 or 3 and 4. Probably that guy screwed all and after a lot of struggling tried to seat the RAM right on those spots, and seeing that it worked left the things like that, instead of searching the cause. Now I will re-install all from scratch after trying to unbend all those little tiny pins.
I will post the results.

 

[arajigar]

SUCCESS!!. All now is going fine. All channels are working right, my 16 GB of RAM work (after touching msconfig to make the system use 16 GB instead of 8), and system boots fas as a bullet.

I will add a resume of all, if someone finds himself in a trouble like this:

TROUBLE: some RAM slots (of same or different channel) are not working

Step 0. Check your motherboard COMPATIBLE RAM list. If they are compatible, turn off your system, unplug the AC cable and go to Step 1.
Step 1. Try to change location of the RAM sticks to see if one of them is not working. Label them with numbers to keep them under control. CLEAN THE RAM SLOTS and the RAM sticks aswell, sometimes we are dirty and we let things get dirty too, and rightly so they do not work.
Step 2. If all Sticks work on one or more channels, go to step 3.
Step 3. Check BIOS to see if all channels are active.If YES goto Step 4. If not, go to Step 6
Step 4. Check if the Voltage is right for your RAM (sometimes BIOS work on different voltages and that could be the cause). Goto Step 7.
Step 5. Clean CMOS and REPLACE MOBO´s Battery, just in case. It does not hurt and could fix all. Goto Step 7.
Step 6. Even if it seem too extreme. Disassemble the CPU heatsink, retire the CPU and with a magnifying glass check if there are some bent pins ON THE SOCKET(yes, I shout because I was so stupid to "not seeing" the pins on THE CPU. MORON MODE: ON), then with some of the thinnest tweezers you can find, try to unbent and align the pins. Reassembly CPU and Heatsink and go to Step 7.
Step 7. Insert again all RAM modules on their slots. Boot your system. IF all is OK, congratulations!!, if not, return to the Step you did not made.

For me, Step 6 was the right solution, but maybe the other steps will save you from this kind of trouble. But, if all fails, maybe is your MOBO that´s dying or already dead.

Thanks to all of you!!
I pick Ko888´s solution as the right one.

 

[ko888]

You didn't pick me as the right solution. You picked Doctor Rob.

When a memory channel is missing on an LGA (Land Grid Array) motherboard, in many cases it is a result of a bent or broken pin or pins in the CPU socket that are not making contact with the land pad(s) on the CPU.

 

[arajigar]

You didn't pick me as the right solution. You picked Doctor Rob.

Sorry!! I have fixed this too! (I´m on a roll).