4GB problems

[geoduck]

I'm having trouble getting my new system to recognize the full 4GB of installed memory. I haven't installed an operating system yet but in the BIOS it shows the total memory as 3505152 K. This doesn't change whether I have the 'memory hole' enabled or disabled. I booted 64-bit linux from a DVD and it only sees 3.5GB as well. The only mention I've found of this problem here is in this link. I'm running an application that requires 3.8GB of memory so I really need the full 4GB. I've had no problems running a similar setup in my older machine with a Lanparty Expert motherboard. Thanks for any help!

[Darkorb]

may i ask what program?

[geoduck]

It's a quantum chemistry program called Molpro. The memory requirements vary according to what molecule is being calculated and what level of theory is being used. It just happens that my latest project needs a minimum of 3.8GB and takes about one week on my current machine to calculate the energy for a single geometry. I plan on calculating many geometries so it would be nice if I could have two machines working on it at once. Thanks for your interest.

[Poisonsnak]

Judging by this random post I found:

 

(from here: http://hardware.mcse.ms/message188850.html)

Note: Memory between 4GB and 4GB minus 512MB will not

be accessible for use by the operating system and may be lost

to the user, because this area is reserved for BIOS, APIC

configuration space, PCI adapter interface, and virtual video

memory space. This means that if 4GB of memory is installed,

3.5GB of this memory is usable. The chipset should allow the

remapping of unused memory above the 4GB address, but

this memory may not be accessible to an operating system that

has a 4GB memory limit.

 

It might be os-related but it's hard to say. Since you're using 64-bit linux it's unlikely but do you have something else to try? Anyway the thread is an interesting read though it seems there is a bit of disagreement in it.

[YeaYea&#33&#33&#33]

rofl, Im getting in on this..Ive been to all 3 of your cities. There isnt a way to make 4gb, Windows only recognizes up to 3gb, but you can change it so the BIOS sees 4gb. It has to do with Win 32bit not being powerful enough to run 4gb.

[geoduck]

Judging by this random post I found:

 

(from here: http://hardware.mcse.ms/message188850.html)

 

 

It might be os-related but it's hard to say. Since you're using 64-bit linux it's unlikely but do you have something else to try? Anyway the thread is an interesting read though it seems there is a bit of disagreement in it.

 

Thanks for your responses. I've been reading through the thread and just received a response from DFI technical support that says basically the same thing. I get the same ~3.5GB whether I look in BIOS, boot 64-bit linux, or run Memtest from a CD. The thing is that I have another machine running a Lanparty UT NF4 SLI Expert mobo with 4GB and it sees all of the memory (after enabling the 'Memory Hole for PCI MMIO' option in the Advanced Chipset Features. A similar feature in the RS482 BIOS appears to be unrelated to running 4GB.). So is this a limitation of the RS482 chipset or of the current BIOS for the machine? Should I look for another NF4 based motherboard?

 

I have yet another machine running with 2GB using a Gigabyte GA-K8NXP-SLI board that from what I've read in other forums will support the full 4GB, so perhaps I will do some swapping and put the 4GB and Opteron 165 in that machine and run the Athlon 64 3000+ with 2GB in the RS482 board. I think the RS482 will overclock better than the Gigabyte so I was hoping to run the 165 in it and hit a high overclock. Oh well.

 

rofl, Im getting in on this..Ive been to all 3 of your cities. There isnt a way to make 4gb, Windows only recognizes up to 3gb, but you can change it so the BIOS sees 4gb. It has to do with Win 32bit not being powerful enough to run 4gb.

 

Well, I've been to a lot of places in B.C. because I'm from Seattle originally, but I've never been to Westbank. Anyway, the problem is that I can't get the BIOS to see the 4GB with this board. I run 64-bit linux so the Win32 limitation doesn't effect me but in BIOS and when I boot linux or run Memtest from a CD it only shows around 3.5GB of memory.

 

This also brings up a question about the specifications for the board. In the manual and on the DFI website it says that this board 'Supports up to 4GB system memory', which I take to mean that you should be able to see all 4GB. Call me crazy.

[Poisonsnak]

Yeah that's harsh. I thought I would try putting 4GB in my RS482 to see what would happen but unfortunately my black slots don't seem to work so I couldn't test it for you.

 

Since the CPU has the memory controller built in I don't think it's a chipset limitation, more likely a BIOS limitation so maybe DFI will come out with a fix? Try harassing them a bit more via email hehe.

[laserred]

Well, you guys are on the right track, but none hit the nail on the head. It has nothing to do with the BIOS, or Windows not being powerful enough. The real reason is because Windows (32 bit) can only deal with 4GB (binary 2^32bits) of memory addresses, and all of your system components use some of these addresses on the data bus in addition to each byte of memory needing its own address as well. So basically, the memory on your video card takes up some of these addresses, and the memory on your X-Fi takes up memory addresses, and these all subtract from the overall available addresses for Windows to handle. So, if you had 2 7950GX2s installed at 1GB total memory apiece, you would not even get the full effect of 2GB of memory (4GB-2GB video-other system components=<2GB for system memory). Windows addresses all system components first (video card, sound card, northbridge, enabled parallel ports, serial ports, game ports, etc- they all burn up memory addresses) and then will assign all remaining addresses to whatever installed memory there is. So the only way for you to be able to use all of your 4GB of memory with your current hardware is to step up to a 64-bit OS (can handle like 16TB of memory addresses I think off the top of my head). You could use a 64-bit LiveCD with Linux if you are not up to installing it on your HDD, but other than that 3.5GB is all Windows can allot to your memory with your current config, unless you disabled everything not used in the BIOS, and used a video card with maybe 4MB of memory, and had no PCI cards in, etc. etc. Sorry.

[geoduck]

Thanks for your input. This actually has nothing to do with Windows since no Windows CD has been within 10 feet of this machine. I've tried 64-bit linux and a bootable Memtest CD (which handles all 4GB on my other machine) and they both show 3.5GB, as does the BIOS. So it appears to be BIOS related since it shows up in the initial memory detection, and unfortunately DFI doesn't seem to want to do anything about it. Don't get me wrong, DFI technical support was great in replying promptly to my support request with an explanation of why I only see 3.5GB, but they didn't offer a solution other than to try a different motherboard and suggest I should be using a workstation class motherboard (which I probably should be, but I'm trying to do this on a limited budget). I'm not going to push them because I don't have the time to wait while they mess with the BIOS. As I stated before, my Lanparty UT NF4 SLI Expert board has an option in BIOS to enable 'Memory Hope for PCI MMIO' and this allows it to see all 4GB of installed memory, but the RS482 doesn't have any such option (although it has one entitled 'Memory Hole' but this seems to be something entirely different.) My Gigabyte NF4-SLI based board also has an option to enable use of 4GB so I'm just going to switch my Opteron 165 and 4GB of memory to it and put my A64 3000+ with 2GB in the RS482.

[laserred]

Hmm. As far as recognizing the memory, you shouldn't have a problem, but obviously something is causing it not to work. I don't know them personally, but maybe ask Happy_Games or RGone for help. They are probably the most knowledgeable guys here, even moreso than DFI support, since they actually tweak the crap out of the boards. Good luck!

[geoduck]

These are the replies I received from DFI tech support (I hope it's ok I'm reposting these here):

 

This is the real situation as it is now understood.

 

The problem that you are seeing is based on an older architecture design for memory addressing. All the systems architecture up to this point were based on a maximum of 4GB of total memory. Nobody really thought, when this standard was designed, that this amount of memory would actually be in use. The problem that has happened is that you have PCI devices that require memory address ranges so that they can properly execute their commands. These address ranges were mapped in the upper sections of this maximum amount. Since nobody thought you would be using up to 4GB these address ranges started around the last 500MB of the memory ranges. This range is called the T.O.M. or Top of Memory range. This is the point in the bios where it places on hold the amount of memory that is required by the various PCI devices that are found on the motherboard. Thus when you have PCI cards or AGP cards installed on your motherboard these devices hold on to memory for their own use and take away from the maximum amount of memory that is available for other tasks. This amount of memory can vary from a little as 200MB all the way to 1GB of memory (or even more in select cases). It just depends on the PCI devices you have and the amount of PCI (including AGP) that you have installed all at once.

 

There is really no way to get around this basic design limitation. The only way to get around these type of issues is to use certain new designs that have brand new architectures (i.e 64-bit designs) that allow memory to be mapped in area's above 4GB. The brand new Intel Xeon designs and the AMD Opteron designs are built around 64-bit technology. This is only ½ of the equation that you would need to find success. You would also need to use an OS that is actually PAE or PAE aware so that it is able to address memory above the 4GB level. To find out about PAE you can search Microsofts website for PAE (Physical Address Extensions) and it will explain this concept and what OS's actually are capable of providing this benefit. Windows 2000 and Windows 2003 would fit both of these criteria. Windows XP on the hand would not allow this type of ability.

Microsoft has addressed this type of issue in the following Microsoft Article (291988): http://support.microsoft.com/default.aspx?...kb;en-us;291988

 

This doesn't really answer why the NF4-SLI chipset gives access to all 4GB and the RS482 doesn't as presumably they are both 64-bit designs since they are for the AMD64 architecture. Then when I asked whether it was a chipset limitation or a BIOS problem I received:

 

Infinity RS482 is certainly not a workstation/server class board for heavy duty use...it is microATX with onboard video and most of them I have seen run in HTPC's or the like...if certain NF4 board seems to fit the situation better then it is certainly what I would be using since chipset architecture is the most likely limit of board with onboard video and internal hard wiring around such chipset configuration. Thank you.

 

This doesn't seem to be a definitive answer regarding chipset vs BIOS and whether it can be fixed for the RS482 chipset as it is for the NF4-SLI chipset.

 

Hmm. As far as recognizing the memory, you shouldn't have a problem, but obviously something is causing it not to work. I don't know them personally, but maybe ask Happy_Games or RGone for help. They are probably the most knowledgeable guys here, even moreso than DFI support, since they actually tweak the crap out of the boards. Good luck!

 

How would I go about asking Happy_Games or RGone specifically for help on this matter? It would be great if they could add anything to the discussion that DFI tech support hasn't, like perhaps if there are any modded BIOS's for the board that might fix the problem? I have Tmod's latest BIOS CD and I didn't find any RS482 BIOS that indicated it fixed this issue. I'm planning to reconfigure my machines tomorrow night so any info that would keep me from having to do that would be greatly appreciated.

[laserred]

Well, what DFI support said is exactly what I said, with the technical terms thrown in for confusion if you're not up to date. I have no idea why your board would not address 4GB of memory if you are using a 64-bit OS, the BIOS and/or board should have no effect on the amount of memory that is addressable, or at least it should not make a difference. Have you checked the memory amount when you are booted into a 64-bit OS? It should show true system memory because of the PAE's DFI mentioned. Maybe try another distro of Linux in 64-bit to see if you can get it that way. Let us know!