Asus p5K-e Wifi/ap and 4 gb ram

[mulvad]

I have ordered an ASUS P5K-e Wifi/AP motherboard and by using the memory-configurator from Corsair found that I want Corsair Dominator cm2x1024-8500c5d modules.

 

When consulting the motherboard manual I can see that ASUS also list these modules on their QVL - great I thought.

 

However I want 4 gb ram on my board and now I am in doubt. When reading the ASUS manual it says:

 

DIMM support:

 

A:Supports one module inserted into either slot, in single channel memory configuration

B:Supports one pair of modules inserted into either channel a or channel b as one pair of dual channel memory.

C: Supports four modules inserted into the yellow and black slots as two pairs of dual channel memory configuration.

 

The manual also states:

 

You may install varying memory sizes in channel a and channel b. The system maps the total size of the lower-sized channel for the dual channel configuration. Any excess memory from the higher-sized channel is then mapped for single channel operation.

 

Apparently the board only supports ddr2-800 in all three modes. However ddr2-1066 is only supported in mode a and b.

 

My questions are:

 

1) Can it be true, that I can not use all 4 slots with the Corsair Dominator cm2x1024-8500c5d modules - and why is that

 

2) Will the modules be able to run in ddr2-800 instead as dual channel ram (this mode is supported by the motharboard according to the manual)

 

3) Will one pair be able to run in 1066 and one in 800

 

4) Why is it not possible to buy dual channel ddr2 Corsair ram with 2 gb on each module?

 

5) Can the correct interpretation of the manual be that the system will use the a-channel as dual channel ram and assign the rma-modules in the b-channel as ram for single channel operation?

 

My last question is more general: I am planning of running Vista 32 bit edition. As I understand, I will not be able to use all 4 gb of ram under a 32 bit operating system ot supporting PAE. I also plan to have an asus Geforce 8800gts with 320 mb ram in my system.

 

Considering the above facts, can anyone give an estimate of the amount of ram I will be able to allocate on my system and how much of the 4gb I will waste?

 

Thanx in advance

 

/Henrik

[DerekT]

 

My questions are:

 

1) Can it be true, that I can not use all 4 slots with the Corsair Dominator cm2x1024-8500c5d modules - and why is that

 

Mainboards and BIOS's are not yet optimized to run with 4 dimm slots populated at full speed. Sometimes you can make it, sometimes you can't so they do not support such a solution. This does not mean you can not run it at that speed, just that testing has shown that often it does not work at full speed with 4 slots populated. You might have to drop to 800Mhz to populate all four slots. This is quite likely.

 

2) Will the modules be able to run in ddr2-800 instead as dual channel ram (this mode is supported by the motharboard according to the manual)

 

This is very likely. I have not seen a one of these boards not handle 8500C5 at 800Mhz. I have seen some make the 8500C5 at 8500C5 so it's a bit of a crap shoot. You just must not expect it, that's all :)

 

3) Will one pair be able to run in 1066 and one in 800

 

No, you can not run the slots independently

 

UOTE=mulvad;309458]4) Why is it not possible to buy dual channel ddr2 Corsair ram with 2 gb on each module?

 

It is possible. 8500C5 is not an easy thing with 2GB DDR2 dimms though as stability issue arise with modules that dense, hence another reason for the new DDR3 platform.

 

5) Can the correct interpretation of the manual be that the system will use the a-channel as dual channel ram and assign the rma-modules in the b-channel as ram for single channel operation?

 

No, if you populate all four dimm banks with identical ram, you will have dual channel access on both banks.

 

My last question is more general: I am planning of running Vista 32 bit edition. As I understand, I will not be able to use all 4 gb of ram under a 32 bit operating system ot supporting PAE. I also plan to have an asus Geforce 8800gts with 320 mb ram in my system.

 

You will not make 4GB with a 32bit OS. All your PCI/PCI-e devices need to address their memory in the 4GB space so you will lose this memory. In other words, your video card has 320MB and this 320MB will need some of that 4GB to address the 320MB of Video RAM. As well, all your other components need some of that DRAM for their addressing overhead. You would need a 64Bit OS to be able to remap addresses above the 4GB area.

 

Considering the above facts, can anyone give an estimate of the amount of ram I will be able to allocate on my system and how much of the 4gb I will waste?

 

It depends on your components. You will very likely find yourself from 3.2 - 3.5GB for an approximation.