System Information Shows I Have 2Gb Ram, When I have 6GB

When you boot up, how much memory shows in the bios?

As Lemur posted check what is showing in Bios on restart if Resource Monitor shows the same as you already posted.

Click Start Orb type in Resource monitor. Open it and click the Memory tab.

Will show memory at the bottom. Post a Snip if you have questions or aren't sure of something.
I'll find a link while you check out Resource Manager.

UNPLUG PC FIRST!
If Bios doesn't show them try reseating the Ram in the slots.
All three. There is a definite snap and the latch catches on its own on an ASUS motherboard. You hear no snap or the latch doesn't close on its own the ram isn't seated yet.
Experience taught me that. One wouldn't seat. I swapped slots and the sticks snapped right in.




Lemur

We did it again.

If you have Run on the start menu, clik it and type msconfig in the box, clik ok. In the System configuration window that comes up, choose the boot tab at the top, clik the advanced button in the mid portion of the window. set the number of cores to max and the memory to the max onboard. After a reboot, check the box that pops up 'Do not show this blahblahblah' and Ok. You should see all of your ram in specs now.

It does you will need to get your manual or download from ASUS.

It will show you how to get to the memory.

Go to the below link. Try the auto detect or curtains on right side.
It will then ask for OS then find your manual.

ASUSTeK Computer Inc.-Support-

See if the Ram is shown in bios and let us know. If only showing 2Gig one stick then follow my post for reseating. Then recheck.

Mike

You can run CPU-Z to see if your MB is seeing all the 6GB

Do not set the cores to max. Leave at the default.