ok this might be a piece of cake for some of you, but i still want to post this here

i recently bought 4gb more for my PC, same brand, same kind, everything seem to work fine. I now have 4 x 2gb installed.

But Windows (7 Home Premium 64bit) says i have 8gb installed, but 4gb usable. I checked the resources monitor and 4gb seem to be reserved, i wonder why.

I heard about the memory remap in the BIOS, here's a photo i took of it:


Is it safe to disable this feature? Will my PC run slower if i disable this feature? Do you recommend me to disable this feature?

And what's the purpose of memory remapping anyway?

This is entirely normal. The BIOS setting is correct, and there is no need to alter it. Why this is happening is that if memory is available, then Windows will use it. But Windows does not give priority to maximising memory available to programs. So for example with 64 bit Windows around 1Gb can be reserved if you have a separate graphics card fitted. And any buffers or caches will expand in line with the amount of physical memory available.

The purpose of all this is to maximize the performance of the operating system and the system hardware. The Windows 7 Resource Monitor gives a more detailed breakdown of how physical memory has been allocated compared to previous versions, so it should give you a better idea of where your memory has 'disappeared' to.

so quickly said, the OS reserves memory to load itself, required/important files and its drivers faster?

and if some reserved memory is unused and, for example, a software need it, then Windows will release it for the software?

Run some programs with the Resource Monitor running. See what information is being reported.

it seem like any game i run, doesn't seem to take more than the free RAM i have.

So tell me, if a game would need more RAM than the free and available RAM, would Windows "release" the unused reserved RAM to become available? If not, tell me what Windows would do in this case, as i'm pretty new with this Memory Remap behavior...

What happens when any application on your PC needs more memory than is available is that Windows uses virtual memory. Virtual memory is created by using the hard drive as a store for the data that would normally need physical memory. This is why a fast, decent capacity hard drive which is kept defragmented will improve Windows performance. If Windows is left on its default settings, this should work perfectly OK.

Having more free memory may help to a degree, but for games once you have the minimum amount needed any extra may give some benefit but not much. If you only had 4GB of physical memory fitted then only around 1.5GB or less would be free. So having 4GB free is quite an improvement, and you are getting some benefit from the amount of physical memory fitted.

I think some of you guys are confused. He has 8GB installed, but Windows can really use only 4GB of it - the remaining 4GB is not used and can't be used by Windows or apps.

If i understood him correctly, he is talking about this issue :


This is usually a hardware issue, try swapping your memory modules, look at your motherboard if your CPU cooler doesn't bend the board (that can have effect on PCB connection to RAM where it stops using this memory because of unreliable connection). Socket 1156 and 1366 are very sensitive to CPU cooler instalation, if you bend the board it is normal on these boards to lose 1,2 or even 3 memory slots because of CPU cooler.

yes i'm talking about this issue (4098 MB reserved). But no, my Megahalems clears all memory slots, it's just that to have access to the first slot (the one the nearest from my CPU heatsink), i have to remove my CPU fan temporarily. So my heatsink doesn't make any RAM sticks bend on the side.

I did noticed the PC seem to take slightly more time to show me the first bootup screen. (Maybe this is the BIOS putting the 4gb into "reserved memory" so taking just a little more time to show the first boot-up screen).

i do have the Memory Remap feature enabled. CPU-Z detects the full 8gb.

SiSoft Sandra also says 4gb, but seem to detect all 4 x 2gb RAM sticks properly.

Not the ramsticks, but the board ! If you screw your CPU heatsink too much, you make the board bellow CPU to bend a little bit, to the sort of U shape. When you do this, you create a problem for a CPU -> CPU pin and board PCB connection. This results in some memory slots not working correctly, so the BIOS detects the memory modules, but doesn't allow them to be used.

I think this is a Windows issue, and definitely not a hardware problem involving the memory modules themselves. If it were then 8GB would not be showing as the installed memory in Windows. A free utility like CPU-Z will give a detailed report on the installed memory if there is any doubt on this point. The motherboard is a current model, and memory mapping is enabled in the BIOS as it should be for 64-bit Windows.

The question is whether the reservation of around half of the physical memory for 'Hardware' is normal or not. As far as I can see, it is normal because the reduction of the amount of free physical memory available by the operating system is a standard Windows feature. And the people that report this as a problem all tend to quote similar figures.

It is a hardware issue lodestar. Either bent board, or one other possibility - RaptorZX3, did you increased VTT voltage or you used the "Auto" value ? If you didn't increased the VTT, then that can be the reason - better alternative (yours) is when memory controller simply disables the secondary memory modules because it can't drive them, in worse alternative the computer becomes unstable.

Try increasing the VTT in BIOS.

Edit: Example of another HW issue resulting in same symptoms :
http://www.tomshardware.com/forum/3089- ... e-reserved

Edit2: Looking at Raptor's BIOS screenshots - increase the memory voltage if needed, increase the IMC (=VTT) voltage. With defaults, 8GB RAM doesn't work on majority of P55 boards.

the XMP profile increases the RAM voltage up to 1.6V

This is really strange...i did opened my PC and did what you suggested, swapping my new RAM sticks, and now it does seem to work, without 4gb of reserved memory, but 2mb of reserved memory instead.

in System informations in Windows, it does show all 8gb without any reserved memory.

Could it be that, in a RAM kit, there is a stick that works better in a slot than the other?

Yes, sometimes it helps.

hmm now i got 2 BSODs, i had a problem with my video card, and now my sound card had set itself to SPDIF, and now it's back with Speakers and SPDIF, and SPDIF being the default selected.

Maybe i'm starting to think the new RAM sticks might be faulty? i might do a Memtest86+ later (i have v4.10 on a bootable cd, and on Ultimate Boot CD also)

Increase the VTT voltage first (IMC in your BIOS). As i said before, Auto usually selects too low IMC voltage for 4 memory modules.

VTT? IMC? where is that? to which voltage? which voltage would be safe?

these RAM sticks are rated to 1.6V, and i use the XMP profile on them (the profile built-in all the RAM sticks installed in my PC), which also overclock my CPU a little (from 2.67Ghz to 2.73Ghz).

The 2 BSODs were in Windows only, not in a game. Also, i have the latest BIOS version for this main board, which is "1003" as i posted this)

Since the last BSOD...i didn't get any for now...and it's been a hour now. I'll turn off the PC for i need to sleep, hoping to see new reply(ies) when i'll wake up)

for information, these are the ones i have in my PC (2 x 2 kits of them):
http://www.gskill.com/products.php?index=243

It's on your second picture, above the memory voltage item. IMC = Integrated Memory Controller, and to be safe with 4 memory modules, you usually need to increase this voltage. And safe values ? Try 1.2-1.25V, that should be enough.