RAM not recognised

  Pine Man 14:53 16 Apr 07
Locked

I have a Mesh PC with an Asus P5N-E SLI nforce 650i Motherboard and I am running Vista 32bit Home Premium.

The mobo has 4 RAM slots and I have just updated from 2 x 1GB to 4 x 1GB RAM.

When I boot up the 4GB of RAM is recognised in BIOS but when Vista boots up I've only got 3GB.

I seem to remember hearing a while back that some mobos have problems reading 4GB but the board can run a total of 8 GB I believe.

Any ideas out there?

  anskyber 15:55 16 Apr 07

The max RAM that Vista is set to recognise is 4 gigs which includes your graphics card memory.

  anskyber 15:58 16 Apr 07

Also click here

  Pine Man 16:01 16 Apr 07

Thanks for the reply - I'm not sure exactly what you mean.

My graphics card is a 512MB DDR2 nVidia GeForce 7300GS (256MB SMA)

  anskyber 16:06 16 Apr 07

As I understand it Vista will only recognise 4 gigs or ram. If like most people the graphics card has it's own ram then it is taken into account as part of the 4 gigs.

  anskyber 16:08 16 Apr 07

I have read somewhere recently where it can be overidden but for the moment I cannot recall where I read it.

  Pine Man 16:39 16 Apr 07

I found an article on Microsofts web site click here which discusses the Physical Address Extension. To enable PAE mode, you have to add PAE to the boot entry in the BCD file. Open an elevated command prompt. Type Run BCDEDIT /SET PAE ForceEnable.

I am not sure what elevated command prompt is but I opened command prompt as an administrator and typed as above but 'run' was not recognised. I tried without 'run' and it was accpted but nothing seems to have changed.

Are you any the wiser?

  thms 19:27 16 Apr 07

Here's a link about Ram limitation on Vista 32

click here

  Pine Man 20:07 16 Apr 07

Thanks for the link.

It turns out to be the same as the thread above yours except it is in clearer English!

Unfortunately it makes no difference. Want to buy 1GB of ram? :)

  Pine Man 10:08 17 Apr 07

It's a hard lesson to learn but it is not always possible to get a 32bit o/s to recognise 4GB RAM.

Because I now have 4x1GB cards all I can read is 3GB. If I take out 1GB I can still read 3GB RAM.

The apparent answer appears to be to reurn one of them and just keep three BUT if you don't have pairs of RAM in the slots the 'dual channel' technology is disabled and the RAM does not work efficiently. The actual answer is revert to 2GB of RAM or keep all 4GB RAM and get 3GB operating efficiently.

What am I going to do? I don't know yet but I'll tick the resolved box and worry about it for a few days!

  HappyTrucker 10:17 17 Apr 07

The Asus boards (or some of them) seem to be able to manage the Dual Channel a little more effectively. In the manual for mine - the P5B-E Plus it says (in unfortunately complicatedese) that if you put a matched pair in one set of DIMM slots and a single stick in another (or for that matter a 512MB and a 1GB in one set of slots) the board will use Dual Channel for the memory it can, and use the overflow as single channel. Don't know how it does it, and TBH don't care much. It claims to do it, and I'll trust it isn't being a bad manual and lying to me.

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