RAM Compatability issue. 16GB detected, 7.9GB useable

[fudonline]

I have recently built my own pc but I am having RAM issues. I have 4x4GB sticks and windows detects 16GB but says only 7.9GB is useable. I have tested all RAM and they all work. If I put 1 RAM stick into slots 1 or 2 (DIMM_A1 or DIMM_A2) the PC will start but if I place RAM in either of the last 2 slots the pc will not start. I rechecked the compatability of the ram with my mobo and it is not in the list. Could this be causing the problem?

 

[Legohouse]

I have recently built my own pc but I am having RAM issues. I have 4x4GB sticks and windows detects 16GB but says only 7.9GB is useable. I have tested all RAM and they all work. If I put 1 RAM stick into slots 1 or 2 (DIMM_A1 or DIMM_A2) the PC will start but if I place RAM in either of the last 2 slots the pc will not start. I rechecked the compatability of the ram with my mobo and it is not in the list. Could this be causing the problem?

Could you let me know which Edition of OS you have? Windows Home basic, Premium etc?

 

[fudonline]

I am running 64bit Windows 8.1 pro.
CPU is AMD FX 8120 8-Core.
I have updated BIOS.
I have reset CMOS.

 

[Tradesman1]

Check in MSCONFIG - the boot tab and see if it is limiting DRAM.....Next and maybe most likely would be to check the DRAM in the BIOS, make sure it's set up correctly and then prob raise DRAM voltage + 0.06 and CPU/NB voltage + 0.10 to help the MC (memory controller) with the 4 sticks, AMD CPU MCs are designed more for 2 sticks than 4 and often need extra voltage to get them running fully

 

[fudonline]

I tried MSCONFIG but I did not see any mention of DRAM at all including under the BOOT Tab.
I looked in BIOS but couldn't see any mention there either so I will be inviting a friend over for him to look at it.
I will post my results ASAP. Thankyou very much for your help so far.

 

[Tradesman1]

MSCONFIG > BOOT > ADVANCED OPTIONS in the upper right of the window

 

[fudonline]

MSCONFIG > BOOT > ADVANCED OPTIONS in the upper right of the window

It says "Maximum Memory" and it's not ticked.
The same goes for the "processors" next to it.

 

[Tradesman1]

Might try loosening the CPU cooler then snug it back down, if one side or the other is too tight can unbalance the CPU and pin contact which can lead to DRAM problems of this sort

 

[fudonline]

Might try loosening the CPU cooler then snug it back down, if one side or the other is too tight can unbalance the CPU and pin contact which can lead to DRAM problems of this sort

Yeah I loosened the CPU fan/cooler but did not work.

 

[fudonline]

Check in MSCONFIG - the boot tab and see if it is limiting DRAM.....Next and maybe most likely would be to check the DRAM in the BIOS, make sure it's set up correctly and then prob raise DRAM voltage + 0.06 and CPU/NB voltage + 0.10 to help the MC (memory controller) with the 4 sticks, AMD CPU MCs are designed more for 2 sticks than 4 and often need extra voltage to get them running fully

I found where to adjust voltage but it hasnt worked either and it took it as far 3.65 Volts. New info that may help in the troubleshooting. CPU-Z says it detects all RAM but that it is running in single channel. Also says that the RAM is 800 mHz when it is actually 1666mHz.

 

[fudonline]

Ok so after extensive trial and error, it looks as though 8GB of RAM is "reserved" but it doesn't say what it's reserved for. I guess if half is reserved, it would explain why it's only running in single channel. Not really sure how to determine why this is happening but it looks like the problem is being narrowed down!

 

[Tradesman1]

Do you have the latest BIOS?

 

[fudonline]

Do you have the latest BIOS?

Yes I have the latest BIOS

 

[Tradesman1]

Starting to sound like it may be a problem with CPU or Mobo, could try taking it to barebones to eliminate any add on devices, then add them one at a time

 

[fudonline]

hmmm, yes im thinking its the mobo too but wanted to make sure before I went and replaced it. I read other forums here from people with the same issue and doing a memory remap (XMP) seemed to work for them but mine was already ticked.