Only 4GB usable of 8GB installed, tried entire checklist by now!

[Erik Friberg]

Ok, so I convinced my youngest bro to build his own PC since it's good learning, but I kind of regret that now. Feels like I've wasted his entire summer job :-/
I was hoping someone maybe knew more about this.

I'm seriously worried we have a hardware problem but have no clue what part might be the problem or if it's fixable by adding more power to the RAM.
When checking computer information in both windows, ubuntu and BIOS it becomes clear that only half of the available RAM is usable. Readings from Cpu-z suggest everything is normal thought.
Interestingly the motherboard finds and reads the size of both installed RAMs. But still sums it up as 3790 Mb usable.

The rig consists of this:
Asus M5A99FX PRO R2.0
AMD FX-8350 8 4.0GHz Black Edition
Kingston 8GB (2x4GB) CL11 2133Mhz XMP Beast Series
MSI GeForce GTX 770 2GB TwinFrozr GAMING-series
Fractal Design Integra R2 750W 80+ Bronze (a bit unsure on this one thought, it changed last min)
Noctua NH-U9B SE2

- We've checked that the mobo is running x64
- We run Windows 8 x64
- Msconfig > Maximum Memory unchecked
- Memcheck gives no error, reads both Rams but seem to test only 3790 Mb
- Tried reseating the CPU and couldn't find any bent spikes.
- Reseated the RAMs several times (desirably placed in blue slots, Slot-2 and Slot-4 counting from CPU)

I found that trying to run one single RAM inserted in either SLOT-3 or SLOT-4 resulted in computer not booting, while both RAM sticks worked perfectly in SLOT-2 resulting in all 4096 Mb ram being available. I'm thinking it could either be faulty hardware or that the mobo is shutting down PORT-3 and 4 for some reason. Insufficient energy? Or I might have to do a RMA. But how do I rule out what hardware is causing the problem?

Thank you very much in advance!

 

[alexoiu]

Try firstly testing the board outside the case (for ruling out a short), single RAM module installed. If still slot 3 and 4 not working, then it's either the motherboard or the CPU (IMC) and I would RMA them both.

 

[Erik Friberg]

Try firstly testing the board outside the case (for ruling out a short), single RAM module installed. If still slot 3 and 4 not working, then it's either the motherboard or the CPU (IMC) and I would RMA them both.

Thanks for the reply! It will be a RMA then! I'll go by your suggestion and RMA them both...

Will update post with best solution when new parts arrived and installed! (if it works)

 

[Tradesman1]

First check your CPU and socket for any excess thermal compound and in particular for bent/broken pins on the CPU, can also try the sticks at 1866 10-10-10-30, 2T spec DRAM voltage and raise CPU/NB voltage + 0.10 - few 8350 CPUs can run at 2133

 

[Erik Friberg]

Firstly; thank you for all your answers!
We finally found a solution to the problem thanks to you! Now when I know the answer I feel a bit stupid...
We had already double checked that all the standoffs for the mb was installed but we weren't able to test the mb outside the case until today. So when we did, we found out that we had added one extra standoff in one of the m-atx slots, which also happened to reside next to the RAM slots. So with it removed, everything worked as it should!
Hopefully the mb isn't damaged from the shortage.

Again, thanks for the answer, I had no clue this problem could be due to a shortage!