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Win7 64bit 6gb RAM shows only 2gb usable

Last response: in Motherboards
November 30, 2010 4:44:04 PM

I don't know if anyone can help me with my problem but here it goes...
I've just built a new desktop pc. I've installed win7 64bit OS and 6GB RAM all the same make/model. My mobo is the ASUS Maximus III Gene. In the POST all 6gb RAM are shown. In the Task Manager/Resource Monitor/Memory it shows a total of 6gb installed (6144mb actually) BUT only 2gb usable (2046mb) with the remaining 4gb (4098mb) listed as "hardware reserved". What exactly does this mean??? Now I do have 2 video cards installed in SLI formation (2 x Asus ENGTS450 1gb GDDR5) but even if that were the problem, shouldn't that only require a max of 2gb of installed RAM as hardware reserved? I am currently running the most recent BIOS for my mobo (ver.2001) and have no other hardware installed except for my ASUS dvd burner.) Anyone have any ideas?
ANY help would be greatly appreciated. Thanks very much.
a c 207 Ĉ ASUS
a c 716 V Motherboard
November 30, 2010 5:00:26 PM

Welcome to Tom's Forums! :) 

H/W Reserved means the RAM is 'unusable' ; obviously you have (2) different sets of RAM {2X2GB} & {2X1GB}. So my first assumption is the RAM is not the same {Speed, CAS timings, Voltage, or Type (incl chips/side)}. In addition, if the RAM is improperly seated or installed incorrectly it too can cause this problem. Also, the 1156 have a VERY common problem of bent CPU pins. There are MANY causes.

1. Run only the {2X2GB}
2. Run only the {2X1GB}
Q - What about the H/W Reserved now?

Please post the following:
1. ALL RAM Part-Numbers and/or link; I prefer a link.
2. What RAM is in What DIMM slots.
3. This image is generally helpful, but I can imaging it already:

4. Confirm the following:
November 30, 2010 7:34:23 PM

Thanks for the response jaquith...

First off my RAM is actually 3 x 2Gb Kingston Hyper (KHX1600c9d3k3/6GX) which all came in one pack. Also, I ran the MemPerfect app that is part of the ASUS BIOS and it checked out. All good. By the way, I've noticed in the BIOS that it says I have only 2 GB usuable RAM. The RAM is slotted in DIMMs A1, B1 and A2 as per the manual.

I'm going to insert the RAM one piece at a time, as you suggest, just to see what happens.

I have taken screen shots of the Resource Monitor/Memory and the Msconfig/Boot/Advanced Options screens but I don't know how to insert or paste them into this msg. Sorry man. (please tell me lol)
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a c 207 Ĉ ASUS
a c 716 V Motherboard
November 30, 2010 8:34:59 PM

That's not in the manual -> "DIMMs A1, B1 and A2 as per the manual."

CPU | A2 | A1 | B2 | B1 | ; install (2) sticks A1 + B1

Then please type it out -> "...insert or paste them into this msg..."
Available =
Cached =
Total =
Installed =
H/W Reserved =

The 'caveat' is yes you CAN use a Tri Channel Kit, BUT you can use 2 of the 3. What happens when A1 & B1 are used?
November 30, 2010 9:58:36 PM

OK - Thanks very very much. Rereading the manual I find it says nowhere that A1,B1,A2 would be the optimal slotting of the DIMMS. So, I inserted them one at a time until I found all 6Gb shows up in the BIOS when slotted A1,B1,B2 (who knew?).

Problem solved... muchos gracias!
April 12, 2013 4:01:11 AM

i had a same problem , check which operating system you are using , 32bit or 64 bit , if you use on 64bit operating system with 64bit processor , it would resolve the issue.