6GB existing +6GB upgrade = 4GB?

[GoldenShadow]

After reading the recent article about adding more RAM I decided to upgrade my system. Everything arrive and looked good, I installed the 3 extra sticks of RAM and the PC booted ok, but I notice that POST only showed 4GB. Also I disconnected all the cords and my keyboard didn't activate when the PC first got turned back on, but it did after the next reboot. After I rebooted, I checked system properties in Windows and it now just 4GB instead of 12GB like I was expecting. It seems like they are all seated, they are flush with each other at least. All of the retaining locks are closed in.

If I can check each DIMM slot in the BIOS and CPU-Z and it shows information for all 6 slots as filled, and CPU-Z reports 12288GB installed.

Specs. The system seems to be stable with all 6 sticks installed, it just reports 4 GB instead of 12GB. Before I added this, that 6 GB worked flawlessly, I've never had even a minor problem with this system's stability. It stays on all day to act as a WMC DVR and plays games and movies without issue.
Windows 7 Home Premium x64
Case: Antec Nine Hundred
Power: Antec Signature Series 850 watt
MotherBoard: MSI X58 Platinum SLI
CPU: Intel core i7 920 2.67Ghz Overclock to 3.32Ghz(reset OC to default for troubleshooting)
RAM: 6GB PC3-12800 1600Mhz (XMP) (tried default speed for troubleshooting)
Videocard: EVGA GeForce GTX 275
Soundcard: Asus Xonar D2X
Harddrive1: IntelX25-M SATA Solid-State Drive 80GB
Harddrive2: Western Digital SATA 1TB
Harddrive3: Western Digital SATA 1.5TB
BD-ROM: SATA LG Super Multi Blue
DVD-RW: SATA LG Super Multi
TV Tuner1:HDHomerun Dual ClearQAM/ATSC Tuners
TV Tuner2:Hauppauge HVR-1600
USB Xbox 360 Wireless Reciever
USB Logitech G15 Keyboard
USB Microsoft Intellimouse Optical


I've read that some other suggestions are to reseat the CPU. somethign which I really don't want to attempt because I'll have to pull the motherboard to remove the heatsync from the CPU.

The RAM that I bought I think is the same exact model I already had in there, a 6GB kit (3x2GB) PC3 12800 1600MHz
Patriot Memory Viper Series. They have a blue heatsync on all the DIMMs

 

[GoldenShadow]

quick update I pulled all the sticks and put a single of the new DIMMs in slot one and it failed to boot. looks like it might be bad RAM. I'm going to test each one to see if any of them are good.

 

[GoldenShadow]

Ok, I tested each stick of RAM one at a time. One of the new sticks fails POST, the other 2 worked. If I put all 5 working sticks in, it shows me 10 GB, if I stick the bad DIMM in slot 6 it shows me 8 GB so I guess I must have had the bad DIMM in slot 4 the first time I installed them

 

[GoldenShadow]

oh, I took it all out and I am RMA the ram for replacements

 

[GoldenShadow]

no I bought from Amazon, they already shipped the new RAM and I have 30 days to ship back the bad stuff.

 

[andrern2000]

That's it. You find the source of problem. So that the broken memory in slot 4 subtracts your current 6GB by 2GB, while blocking access from slot 5 & slot 6 from contributing. Congrats!

 

[GoldenShadow]

Replacement RAM arrived and was installed a few days ago and its been working rock solid ever since.

 

[GoldenShadow]

Best answer selected by GoldenShadow.