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4GB Memory in ASUS P5B-VM


markiehill

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Posted

This mboard is running the latest official bios, on boot it displays 2800MB as the memory size even though i have 4GB on board. If i switch the option in the bios to remap memory, the bios will then see the full 4GB but Windows XP (64 bit) crashes out at the boot screen.

 

Any ideas would be most helpful, and yes i do need 4Gb its for huge statistical number crunching.

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Posted

I checked your how to read your memory module image, but it does not have the part number underlined for my type, here are the numbers that are on it:

 

CM2X1024-6400 5-5-5-12 800 Mhz

 

XMS6405v5.1

 

XMS2-6400

 

187057 0634287-7

 

I have made no performance tweaks, essentially everything is set to auto.

 

Mark

Posted

some more information on this problem.

 

I have run memtest on the pair of individual sticks only, this is fine no problems.

 

As soon as i put the 4 sticks in , i get errors in the 6434MB memory range and the machine reboots, i guess the high number is to do with the bios remapping.

 

Any thoughts ideas would be most welcome.

 

Mark

Posted

the bios will only allow up to 1.95 i think, and it goes red when i do this, so i didnt, the furthest i took it was 1.90 and that made not a bit of difference.

 

The power supply is 380W nothing else is on the machine, other than a cdrom

 

I am away from the machine for the next couple of days, so cant do much but please post suggestions here so i can try them when i get back. Maybe i should return the motherboard ? Is there a better board for this setup, it did say max 8GB so i trusted it :)

Posted

With a 380w PSU, you could easily be having a power problem. Will the system run a pair of DIMMs stable? If all the modules are OK individually, my guess is the PSU. For that system, the new Corsair HX520 would be a solid choice and the HX620 if you intend to add LOTS of peripherals or do some crazy OCing.

 

Mike.

Posted

yes it will run a pair OK with no issues, it will also run with 4 without the remap option turned on in the bios, the minute i put that on all hell breaks loose :)

 

Mark

Posted

I tried to reinstall the OS , this just hangs at random points with a IRQ_NOT_LESS_OR_EQUAL error.

 

Memtest fails trying to read and write to the 6400MB range, is this to do with the bios remapping option that makes the memory address look so large.

 

Anyway point being i have had all 4 memory modules in and running with no problems as long as i dont enable the bios remap option, if i do then nothing works. Is it feasible that the modules draw more power with the option switched on ?

 

Mark

Posted

i have put a 500w power supply in this which still does not work. What i have found is that out of 10 reboots i can get one stable memtest pass, which is confusing things somewhat.

 

I have never seen a situation where a machine runs fine one boot and then fails the next, also all the memory errors are totally random i.e. never the same address twice, its driving me nuts.

 

btw this is all in memtest, any pointers (no pun intended) would be more than welcome.

 

Has anybody ever got this board running with 4gb of corsair memory ?

  • Corsair Employee
Posted
Please try and set the memory frequency manually to DDR2-667 and see if it will get thru the install of the O.S. and I would let it do a full format of the HDD do not let it do a quick format.
Posted

I have tried it at 667, same problems, loads of bad addresses in the 6GB range.

 

Quite frankly i am starting to wonder if this board is a piece of junk when using 4GB.

 

I have contacted asus , but no reply.

 

Mark

Posted
You need to turn on bios remapping to see the extra memory, though this may be the start of your problems as in my case, let me know if your system is stable when you do this.
Posted

Hi Mark,

 

I think I have a workaround for you. I have changed the Memory clock Freq to533MHz, DDR Voltage: 1.95v and set the switch to remapping. Now it works fine. The problem I think is that the ASUS P5B-VM doesn`t support DDR voltages more the 1.95V!! 2.1V is needed for 800Mhz! I hope ASUS will fix this ASAP. :sigh!:

 

cheers

 

Walter

  • Corsair Employee
Posted
Mark I am sorry but that would suggest a problem with the Bios and I would suggest calling ASUS to see what they say 502-995-0883 is the phone number!
Posted

Sorry to hijack the thread but I'm getting more and more confused about which memory modules will work with the P5B-VM. I'm looking for a 2*512 matched pair but couldn't find the motherboard listed in the corsair configurator.

 

Would either of these memory matched pairs work with this board?

TWIN2X1024A-6400 (http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=202607)

TWIN2X1024-6400C4

(http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=447064)

 

They both seem to need 2.1v? Any help would be much appreciated. :):

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