# Problem with 4GB and Asus P5B



## melkhior (Oct 7, 2009)

Hi, 

The problem I have is that I have to decide between: 

- That the bios detect my RAM 4Gbs correctly but not Vista x64 and W7 x64 boot (stay/freezes on the loading screen). 
- The BIOS does not detect my RAM 4Gbs but both Vista x64 and W7 x64 boot properly. 

The bios only detect 4GB if I activate the "memory remapping", but then, both vista x64 and W7 x64 boot.

My PC is: 

- C2D e6300 
- 4 GB of RAM (2 * 2GB identical)
- Asus P5B (Motherboard)
- ATI HD4870 

I tried to put the memory on other sockets but it doesn't worked and I ran memtest86 before I went to sleep and when I woke up it showed me 0 errors.

Any recommendations? The version of the bios is the latest...

Thanks to all 

PS: Forgive me for my english


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## Mussels (Oct 7, 2009)

memory remapping must be enabled to access all the ram.

I suggest reinstalling windows after enabling the feature, see if that works. Windows simply may not like it being changed after the OS has been installed.


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## melkhior (Oct 7, 2009)

Well, I enabled it before install windows. It's always the same history, windows installs correctly (with memory remapping enabled) but when it's gonna boot the pc freezes.

BTW, thanks for that fast reply


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## Mussels (Oct 7, 2009)

strange issue, to be honest.

does windows boot if you leave memory remapping on, but take one stick of ram out?


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## melkhior (Oct 7, 2009)

I will try 

edited:

Oks, I tried it. With memory remapping enabled and one stick boot correctly (I tried with each one and both boot correctly).

Should I reflash the bios? Should I install both sticks in the same channel? (losing dual channel...)

Thanks in advance


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## Mussels (Oct 7, 2009)

well at least we ruled out it being a problem with the OS not liking 4GB of ram.


normally i'd be thinking it was memory timings, or incorrectly set RAM voltage - but its odd that it would work with memory remapping off.


does the BIOS have any other options near memory remapping that may be related? (in the same menu)


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## melkhior (Oct 7, 2009)

Mussels said:


> normally i'd be thinking it was memory timings, or incorrectly set RAM voltage - but its odd that it would work with memory remapping off.



In fact, I set it manually but the OS didn't boot. 



Mussels said:


> does the BIOS have any other options near memory remapping that may be related? (in the same menu)



No...

EDIT:

Pic from northbridge configuration:





Pic from what bios detect:





If I memory remapping it's enabled here shows 4 GBs.


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## Mussels (Oct 7, 2009)

well i'm stumped at the moment.

lets look at the software side:

What OS's have you tried - you mention windows 7, but not what build (beta, RC1, RTM)


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## melkhior (Oct 7, 2009)

Well, I tried with Windows 7 ultimate x64 final version and Vista ultimate x64 + SP2.

Thank you another time for the patience


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## Mussels (Oct 7, 2009)

i'm stumped.

lets wait and see what other suggestions people come up with.


i found this via google



> 2) Default The importance of tRFC and 4/8GB of memory
> If you are running ANY type of Intel or 680/780i chipset DDR2 motherboard with 2x2GB for 4GB or 4x2GB for 8GB of ram, tRFC will have a major impact on how your system will run.
> 
> you may see option for tRFC called "Refresh to activate delay" so please don't be fooled. If your bios only goes as high at 42 you are going to have issues with speeds much over 900MHZ, in some cases some boards even have issues at 800MHZ.
> ...



its an older guide, but you do have an older chipset from the era before 2GB ram sticks came out so this may well apply to your situation. 

whats your TRFC setting set to, in your BIOS?


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## melkhior (Oct 7, 2009)

Doesn't work... 

Thank you a lot for the effort


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## mastrdrver (Oct 10, 2009)

Yea the tRFC maybe causing problems as Asus didn't implement a way to allow anything higher than 42. This can cause problems with 2gb sticks. Quick way around that is to clock the memory down to 667mhz if your running 800mhz since the tRFC won't need to be as high.


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## Mussels (Oct 11, 2009)

mastrdrver said:


> Yea the tRFC maybe causing problems as Asus didn't implement a way to allow anything higher than 42. This can cause problems with 2gb sticks. Quick way around that is to clock the memory down to 667mhz if your running 800mhz since the tRFC won't need to be as high.



good advice.


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## newtekie1 (Oct 11, 2009)

Had this problem with my P5B.

Fixed it by upping the Northbridge voltage(can remember what to off the top of my head), and raising the memory voltage to 2.0v.

The P5B is very tricky when it comes to memory.


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## xev11 (Oct 11, 2009)

what bios do you have? is it the latest one? also as newtekie said, increase the voltages on nb and memory


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## melkhior (Oct 14, 2009)

newtekie1 said:


> Had this problem with my P5B.
> 
> Fixed it by upping the Northbridge voltage(can remember what to off the top of my head), and raising the memory voltage to 2.0v.
> 
> The P5B is very tricky when it comes to memory.



Tried and doesn't work 

I raised the NB voltage to 1.40v first and then to 1.55v and the memory voltage to 2.0v.



> Yea the tRFC maybe causing problems as Asus didn't implement a way to allow anything higher than 42. This can cause problems with 2gb sticks. Quick way around that is to clock the memory down to 667mhz if your running 800mhz since the tRFC won't need to be as high.



Doesn't work also 



> what bios do you have? is it the latest one? also as newtekie said, increase the voltages on nb and memory



I have the latest one...

Thanks to everyone


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## mastrdrver (Oct 14, 2009)

melkhior said:


> > Yea the tRFC maybe causing problems as Asus didn't implement a way to allow anything higher than 42. This can cause problems with 2gb sticks. Quick way around that is to clock the memory down to 667mhz if your running 800mhz since the tRFC won't need to be as high
> 
> 
> Doesn't work also



Did you try giving the nb more volts at the same time? Also, leave the timings on auto and clock the memory to lowest mhz speed allowed.


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## temp02 (Oct 14, 2009)

Try this: enable memory remmaping so that the BIOS reports the full 4GB of ram installed, then install the Intel Chipset Utility and see if Windows still reports 2GB.


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## melkhior (Oct 14, 2009)

mastrdrver said:


> Did you try giving the nb more volts at the same time? Also, leave the timings on auto and clock the memory to lowest mhz speed allowed.



I tried with 1.55V on NB and 2.0v on memory 533 mhz, 667 mhz and 800 mhz but doesn't work none of them...



> Try this: enable memory remmaping so that the BIOS reports the full 4GB of ram installed, then install the Intel Chipset Utility and see if Windows still reports 2GB.



If the memory ramapping is enabled the OS doesn't boot up.

I can't understand why it doesn't work... And it's strange cause memtest86 run perfect with memory mapping enabled.


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## temp02 (Oct 14, 2009)

Exatcly what I tought, the problem does not reside on the hardware but on the software (either some Intel chipset driver or the Windows boot loader). But when you say that it doesn't boot do you mean that Windows fails to boot (crash/reset while loading), the boot loader doesn't even run (simple black screen) or Windows loads but resets/crashes when reaching login screen?
If it "freezes" the way I'm thinking it might (as soon as the boot loader appear), try to reinstall the Intel chipset driver, even if you have to install it with memory remaping disabled, after you reboot the new driver should load and support memory remaping (hopefully, or else you might need to contact Intel).

*EDIT:* and in case it's not Intel's fault check if this info is helpfull


> ...
> To enable PAE mode, you have to add PAE to the boot entry in the BCD file. Open an elevated command prompt. Type
> 
> ```
> ...


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## melkhior (Oct 14, 2009)

I mean that windows freezes on the loading screen.

I will try. If it doesn't work I will try install another time with the memory remapping enabled. Then, the first time I'll install will be the intel driver...


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