Have 16gb but only see 12gb on the BIOS. Is my Video Card responsible for that?

[Cabeza2000]

This is my PC. Got it two days ago and expended most time configuring tweaking and even doing some OC (nothing fancy, I used the built-in wizard).

The only thing I could not fully figure out yet is why I see 12GB RAM and not the 16GB ram...

Following some research I see plenty of people that had the same issue and posted the same question in many other sites. I read a lot of answers and it seems it may be the video card reserving memory from the system (I am mainly trusting what the user dragonlord wrote here.

CPU-Z and Speccy are showing 16gb so that may be the case.

Next step I took is accessing the sys info from Nvidia. The key information is the following:

Total available graphic memory: 10gb.
Dedicated video memory: 4gb GDRR5
System video memory: 0
Shared system memory: 6gb

And this is the point where I am puzzled. Does the "Shared System memory" means that the graphics card reserved system memory to the point that the BIOS is not even showing it? Is this normal?

I mean, the DRAM status is totally not showing the dimm as you can see here. It was the same before the OC.

I know I may need to check if I have a faulty one but in such case I would not expect CPU-Z and Speccy to see it, so I doubt it.

At this point I am 50% thinking this may be normal (specially with so many others posting similar experiences) and there is nothing I should do, and the other 50% toward continue researching and see what may be the problem.

Task Manager is showing the same as the BIOS.

Any advice is very welcome.

 

[Shmee]

Check to make sure the RAM is seated correctly, may need to be reseated.

 

[JoeRambo]

Probably digging too deep. I'd start with what Shmee recommended and then would move on to resetting OC to default speeds. I've had case in the past where OC on X58 chipset and full 6 mem stick would pass all stability but would not show just like You're experiencing. I'd start by manually dropping memory multiplier to achieve 1866 speed just to be sure if that is not the case here.

 

[tcsenter]

You have a DIMM module not being detected or working! Make sure you populated the correct slots according to the user manual for four modules. Try removing the DIMM, check the contacts and slot, and reinstall it.

 

[tcsenter]

I mean, the DRAM status is totally not showing the dimm as you can see here. It was the same before the OC.

I know I may need to check if I have a faulty one but in such case I would not expect CPU-Z and Speccy to see it, so I doubt it.

Modules since the late 90s have used a SPD chip to report module capacity, organization, and other data. This SPD chip has it's own bus and pins in the DIMM socket. As long as the SPD chip and bus are working, utilities like CPU-Z that simply read or poll SPD data will still report the module's programmed capacity, even if the module itself (the memory components) is not working. You could actually build a 'fake' module that has no memory chips, just an SPD chip and it would still report whatever capacity is programmed into it.

 

[Cabeza2000]

Thanks all for your replies. And thanks to tcsenter I now understand why Speccy and CPU-Z are giving me 16gb and not 12gb as the task manager and the BIOS.

The only part still not fully clear is whenever the video card is reserving physical memory or not, but even if it does, I guess it does not make much sense that such reservation will cause the BIOS to not show the dimm at all.

It is time to follow most of the advice here and see if the dimms are seating correctly... I will probably call the store now as I need to break the warranty seal, which usually means nothing but the computer is just a few days old.

 

[ShintaiDK]

The card shouldnt reserve memory at such low range on a Haswell system. Specially not Haswell-E.

 

[DustinBrowder]

I haven't seen system reserve more than 500mb memory unless it had an IGP and it was set manually in bios to use max memory all the time.

Either way it should show as 16GB in the bios, I'd follow the advice of others and check the dimm's. Make sure you put them in one by one and check if one of slots is faulty!

 

[crisium]

DDR4 has to be seated perfectly. I had a similar problem. I was only showing 12GB in bios, tried reseating, and then only got 8GB! But sure enough I got 16 eventually. I had to be very firm with pushing them down even after they locked in. I'm not sure if your mobo shows which slots are active, but mine did. That way you know where the problem is.

 

[tcsenter]

The only part still not fully clear is whenever the video card is reserving physical memory or not, but even if it does, I guess it does not make much sense that such reservation will cause the BIOS to not show the dimm at all.

That shared system memory metric reported for graphics even when you don't have UMA sharing graphics device is due to video resource (memory) virtualization implemented in Vista and later (per WDDM), similar to (but not exactly) what the AGP aperture feature did during the AGP days.

Video Memory Virtualization - A Brief Guide

 

[JoeRambo]

That shared system memory metric reported for graphics even when you don't have UMA sharing graphics device is due to video resource (memory) virtualization implemented in Vista and later (per WDDM), similar to (but not exactly) what the AGP aperture feature did during the AGP days.

Video Memory Virtualization - A Brief Guide

It should not change what BIOS or Windows shows. It is module not seated correctly. His DIMM_C1 is not functioning either due to lack of contact or not beeing able to handle clock or timings.
Please don't dig too deep and save future googlers from pain.

 

[tcsenter]

It should not change what BIOS or Windows shows. It is module not seated correctly. His DIMM_C1 is not functioning either due to lack of contact or not beeing able to handle clock or timings.
Please don't dig too deep and save future googlers from pain.

He specifically mentioned it was unclear to him as an open question, what this 'shared system memory' thing was doing. I clarified it for him: the 'shared system memory' is not where his 'missing' 4GB is going. Don't tell me how to resolve or address questions people have raised.