ASUS P7P55D Pro - only half of total memory is available

CurseTheSky

Diamond Member
Oct 21, 2006
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Well, this is annoying. First, I found out that "Due to Intel Spec..." memory over 1333MHz (DDR3 1600, like mine for example) will only run at single channel. Of course, I bought DDR3 1600 memory. Ugh.

Anyway, on to the real problem:

Like many others, Windows and various tools such as CPU-Z are able to detect all four gigs of RAM that I have installed - 2x2GB. However, opening task manager and checking out the performance tab, I can see that only 2GB of memory is available to the OS. Usually the quick fix is to go into the BIOS settings and enable Memory Remapping. The problem is, I've already enabled it, and I'm still only getting 2GB available.

[*]The motherboard is an ASUS P7P55D Pro
[*]The BIOS was recently updated from the original release BIOS (v. 0209 or something like that) to v. 0606, and the problem still persists
[*]The memory is 2x2GB G.Skill F3-12800CL9-2GBRL (4GB total)
[*]Removing either stick results in both Task Manager and CPU-Z reporting 2GB available (as expected); the system runs fine on either stick alone, or both sticks together (aside from the OS not being able to use all 4GB)
[*]The memory is installed in Channel A, slots 1 and 2 (second and fourth slots on the motherboard, like the manual suggests; shows as slots 1 and 3 in CPU-Z)
[*]The processor is an i7 860 on all auto speeds / voltages
[*]Nothing has been overclocked or over-volted; everything has been left on auto (stock) settings

Any ideas?

Thanks.

UPDATE:

Apparently the devil is in the details. My original statement that anything over DDR3-1333 will run in Single Channel mode is incorrect. Instead, according to Intel's spec, only one DIMM per channel will be addressable (or available to the OS, or however you want to put it). In other words, if you're running DDR3-1600 like me (or something higher), you'll need to put one DIMM in one channel, and the second DIMM in the other channel. If you're running four DIMMs, you may need to get DDR3-1333 instead, unfortunately.

I originally had one stick of memory in memory slot A1 and one in slot A2 (according to the P7P55D Pro manual). I removed the stick from A2 and put it in slot B1 and everything works fine. Too bad my memory is still running in Single Channel mode... now I wish I had gone for cheaper DDR3-1333. :(
 

n7

Elite Member
Jan 4, 2004
21,281
4
81
Interesting.

Here's the thing though, the max supported speed for s1156 (@ stock) is indeed DDR3-1333, that is, it's using the 10x RAM multiplier.
You want to use the manfacturer implemented 12x one.

Better solution: OC.
Seriously, OC.

I really hope you didn't buy an OCing mobo + OCing RAM to run stock.

All you need is BCLK @ 160 to get DDR3-1600 dual channel.

I suspect even the Asus OC newbie software probably has a preset button you can hit that'll get you those speeds w/o you even needing to have a clue what to do.

 

CurseTheSky

Diamond Member
Oct 21, 2006
5,401
2
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Originally posted by: n7
Better solution: OC.
Seriously, OC.

I really hope you didn't buy an OCing mobo + OCing RAM to run stock.

Of course not. :p

I got unexpectedly caught up in work over the past few weeks and I just haven't had any time to tinker (if something goes wrong with my system over night, I'm screwed).

I'm chomping at the bit waiting until I can take the risk of pushing this thing on both air and water. With the recent article (from Anandtech) about burning out Foxconn sockets, I won't be doing anything crazy, of course. :p
 

dbdynsty25

Member
Jun 22, 2004
109
0
0
I bought the same processor and same mobo, but now I'm worried that my ram won't work with it. I picked up 8gb of G.Skill Ripjaw DDR3 2000 (PC 16000)...I haven't done any overclocking in years, but was thinkin' about giving it a try this time. I am just wondering if I should just return it and pick up some 1333 and just be done with it. LOL.