old motherboard BIOS reserves 1027MB of 4096MB total

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Here’s a tough one for all you senior experts:

I’ve converted an aging Intel D915PGN motherboard to a backup storage server, and very recently installed a trial OEM copy of Windows 7 Ultimate 64-bit.

That fresh install completed successfully, even though only 2,048 MB of RAM was installed.

The motherboard, video card, Gigabit Intel PCI NIC, 2 x RAID controllers and all attached HDDs and SSDs appear to be working fine.

Most recently, I added 2 more GB of Corsair DDR-400, for a new total of 4,096 MB.

The newer RAM has slightly slower SPD timings, but I believe the chipset simply runs all DIMMs at the slower SPD timing: 3-4-4-8 vs. 3-3-3-8

CPU-Z confirms 4 x DIMMs of DDR-400 running at 200 MHz with SPD settings of 3-4-4-8 .

I ran Windows Memory Diagnostics and it found no errors.

Here are the symptoms:

during POST, the mobo BIOS reports:

“Memory consumed by system resources:  1024 MB”

upon reaching the Windows 7 Desktop, Resource Monitor reports:

Installed:  4096 MB

Hardware Reserved:  1027 MB

Total:  3069 MB

Windows Task Manager also reports the same “Total:  3069 MB”

I tried disabling all of the on-board features that I don’t need, such as the slower RJ-45 port, USB ports, parallel and serial ports, etc.  But, these changes made no difference.

It just seems rather excessive that the motherboard BIOS would assign roughly one-fourth of the total physical RAM installed even BEFORE launching the OS.

There may be a newer BIOS for that motherboard, but Intel stopped building motherboards a long time ago, so it’s not likely that I should even try to request their help.

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From the manual:
Remove the PCI Express x16 video card before installing or upgrading memory to avoid interference with the memory retention mechanism

cheers, Paul

1 user thanked author for this post.

SupremeLaW

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THANKS!

An x8 RAID controller is now installed in that one x16 PCIe slot.

Model is Highpoint RocketRAID 2720SGL.

(See Figure 1 above, from the motherboard User Manual.)

Video is now being handled by a PCI video card installed in the first PCI slot next to the single x16 PCIe slot.

Model is PNY GeForce 8400GS with 512MB of on-board DRAM.

Video appears to be OK, except that the limited bandwidth of PCI is rather obvious, compared to PCIe.

That manual advice is not relevant because all 4 DIMM slots are populated;  and, Windows Memory Diagnostics task found zero errors in any of the DIMMs, both old and new.

There is no physical interference with the memory retention mechanisms because the RAID card has a smaller x8 edge connector.  Again, see Figure 1 above.

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I’m almost sure now that the error must be in the motherboard BIOS somewhere:

during POST, it polls the CPU and reports what it finds:  Intel 3.8 GHz

then, it polls memory and reports what it finds:  DDR-400

then, just before scanning all available memory aka “slow boot” option, the BIOS reports:

“Memory consumed by system resources:  1024 MB”

Clearly, at that discrete point during STARTUP, the OS has not yet launched, and that is another reason why I strongly suspect a bug in the motherboard BIOS.

I’ve  highlighted with red rectangles the symptom detected by Resource Monitor in Windows 7 Ultimate 64-bit version:

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3,069 + 1,027  =  4,096

As such, Resource Monitor appears to be correctly accounting for all available physical DRAM (DDR-400:  4 x DIMMs @ 1GB)

The sheer amount of “1,027 MB” appears to be mostly unnecessary, in light of the 512MB that is on-board that PCI video card:  PNY GeForce 8400GS

 

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Is onboard graphics enabled in BIOS?

cheers, Paul

1 user thanked author for this post.

SupremeLaW

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The Intel D915PGN motherboard does not support integrated graphics.

There are 3 choices for video in the motherboard BIOS:  AUTO, PCIE, EXT PCI

It’s currently set to AUTO, and the PCI video card is the first component the motherboard BIOS accurately reports during POST.

I tried to find detailed documentation for the BIOS options, but Intel doesn’t build motherboards any longer, and the documentation I do have does not cover those options.

I found this today:

http://www.aslab.com/support/kb/133.html

 

 

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spelled precisely, the video options in the BIOS are:

PCIE Graphics (PEG)

Ext PCI Graphics

Auto

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This website has more information about BIOS video options, for slightly different models of that motherboard:

https://www.cia.gov/library/abbottabad-compound/69/69410DB208D1F3627C71F6A6C6BA572C_English.pdf

Apparently, the authors of that manual distinguished integrated graphics and add-on graphics with the nomenclature “Int” and “Ext”, respectively.

My version of the D915PGN has no port for IGD (Integrated Graphics Device? or Display?)

I just now inspected the rear I/O panel, and a VGA connector is missing;  the I/O shield is empty there.

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I’m pretty sure it’s a “feature” in the BIOS currently installed in that motherboard.

FYI:  before I added 2GB of DDR-400, there was only 2GB total memory.

Now, there is a total of 4GB of Corsair DDR-400 running at 200 MHz (i.e. factory default), 3-4-4-8 SPD timings.

With only 2GB total, I ran into unexpected problems when updating Firefox:

upon clicking the update option in Firefox “Help”, the system crashed the video driver and the monitor went BLANK, requiring a RESTART with the front panel RESET button.

That was a pretty strong indicator of a memory management fault.

From the documentation at the link above, it confirms a “legacy PCI” problem.

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https://lists.opensuse.org/archives/list/amd64@lists.opensuse.org/message/UYFH2IJOOZBXSSH6OJTXQA6YEQQA636Y/

[begin quote]

… if you have, say a video card with a 256MB video buffer, then
at minimum, you’ll have at least a 512MB “PCI hole”, since the BIOS
needs to be the last part before 4GB and the video buffer must be
aligned to a 256MB (i.e. native size) boundary. If it was a 512MB
video buffer, then you’d be guaranteed to lose at least 1GB.

So, it’s easier then you’d imagine to lose 0.5GB or even a full 1GB
in the PCI hole with some high-resource add-in adapters. My server
box loses about 870MB without memory remapping enabled. Though I
guess I asked for it with that 256MB video card and the other add-in
adapters I use.

This is not a Linux vs. MS-Windows nor an AMD vs. Intel thing. It’s
just a fact of how the PC architecture works.

[end quote]

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That refers to x86, not the x64 OS you seem to have installed.

1 user thanked author for this post.

SupremeLaW

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See above where I quote messages on-screen during POST and BEFORE any OS is launched.

My best current theory is summarized in my most recent REPLY:

The BIOS appears to be reserving, and doubling, the amount of video RAM that is on-board the PNY PCI GeForce 8400 GS video card.

In the results of my Internet search, this has been called the PCI “memory hole”.

So, a good test of that theory is to try a different PCI video card that has much less on-board video RAM e.g. 64MB.

I already did try a PNY model NVS 280 PCI video card with 64MB of on-board RAM, but there was no video output during POST (BLANK monitor).

Also, a second test is to remove the PNY PCI video card, and replace it with an x1 PCIe video card.

In anticipation of the latter test, I’ve already re-wired some of the SATA cables, and removed a StarTech PEXESAT3221 SATA adapter.

Right now, I’m shopping for a quality x1 PCIe video card.

Any recommendations?

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see solution below …

 

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SUCCESS!

I removed the PNY GeForce 8400GS PCI video card, and

replaced it with a PNY NVS 280 PCI video card with only 64MB of on-board RAM.

Now, during POST and before launching the OS, the BIOS reports:

“Memory consumed by system resources:  512 MB”

and

“Available memory:  3,584 MB”

 

In Resource Monitor:

“Hardware reserved:  515 MB”

 

And, in Windows Task Manager: 

“Total Physical Memory:  3,581 MB”

 

Bottom Line:  the 512MB on-board RAM in the model 8400GS was causing the motherboard BIOS to double that amount and reserve it for system resources.

A similar video card with 64MB reduced the amount reserved for system resources by 50%.

When only 2GB of DDR-400 was installed, the NVS 280 trashed the video driver, most probably due to this “feature” in the memory management logic of the motherboard BIOS.

 

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Here’s a useful comparison to an ASUS P5WD2 Premium motherboard, now populated with 8GB of memory:

 

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It’s a chipset limitation in this case. The i915 doesn’t support remapping of memory above the 4GB boundary. So even if you have a 64-bit OS, you still have the same limitations as you would with a 32-bit system.

My memory is a bit hazy on this one but I think even the i945 doesn’t support this; you need to go to the 965 to make use of the full 4GB.

2 users thanked author for this post.

SupremeLaW, satrow

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The Resource Monitor screen shot above confirms what you wrote.

The User Manual for our ASUS P5WD2 Premium motherboard says this about that chipset:

Northbridge:  Intel 955X Memory Controller Hub (MCH)

Southbridge:  Intel ICH7R

 

Also, we have XP running on that same motherboard.  Windows Task Manager reports 3,144 MB of “Physical Memory” even though it has 4GB installed.

 

THANKS AGAIN!

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To free up larger PCIe expansion slots, we have this AMD Firepro 2270 working fine in a newer motherboard — the ASUS P5Q Deluxe with Intel Q6600 overclocked:

AMD FirePro 2270 100-505972 512MB DDR3 PCI Express 2.1 x1 Low Profile Workstation Video Card

https://www.newegg.com/amd-100-505972/p/N82E16814195103?Item=N82E16814195103

 

It’s obviously slower because of the bandwidth limitation of an x1 PCIe socket, but otherwise it performs AOK.

In general, we don’t fuss with video on PCs that are re-purposed as backup storage servers.

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