24GB RAM showing up as 16GB

[yhelothar]

I'm using Win7 Ultimate. When I go to computer properties, it says 24GB (16.0 GB usable)

It worked fine initially when I installed it.
I remember tuning some of the cas settings in the bios(and perhaps others) and it stopped working after that. The problem is, I don't remember what I tuned. It was two months ago.

I'm using eVGA x58 SLI LE mobo with i7 920 and 6 sticks of 4GB DDR3 1600 cas9

I have all the timings/frequency in the bios set to what the ram is rated at on the sticker.

 

[BFG10K]

Try setting your BIOS to factory defaults.

 

[yhelothar]

It doesn't POST with all 24GB ram at factory defaults. I need to plug in 12GB, set the rated ram settings, and put in the other 12. :\

 

[yhelothar]

I googled to see if this is related to my motherboard, and apparently it's an infamous issue with the eVGA X58 SLI. It doesn't look like anyone knows the reason and many different things people try fixes it. One of them is to up the VTT, one of them is to change ram brands, another person fixed it by changing their 980x to a 920. :\

 

[fuzzymath10]

There are soft limits in Windows as well. For example, Windows 7 will only recognize 24GB if you have Professional or Ultimate; Home Premium has a max of 16GB.

Edit: oops, saw you had ultimate

 

[John Connor]

You are way off. http://msdn.microsoft.com/en-us/library/aa366778.aspx#physical_memory_limits_windows_7

 

[Topweasel]

There are soft limits in Windows as well. For example, Windows 7 will only recognize 24GB if you have Professional or Ultimate; Home Premium has a max of 16GB.

Edit: oops, saw you had ultimate

I thought it was more like 192GB?

I know my system sees all 32GB I have installed.

 

[fuzzymath10]

Just to clarify (a week later...) that what I meant was that if you have 24GB, you need at least W7 Pro to be able to recognize it all; I did not mean that the max for those versions is 24GB.

 

[john3850]

When I went from 6GB to 18Gb I needed to raise the memory from 1.46 to 1.54v to boot.
I would start off with DDR3 1333 (PC3 10666 and 2t. which op did here when going to 24gb to start off with.
Also raising the vtt from 1.28v to 1.34v wont hurt either.