Question I have 8gbs of memeory installed in my motherboard, but only 4gbs is usable. Why is this?

[WCB_01]

My PC is running a xeon x3430, with an asus p7h55/usb3 motherboard. Windows knows I have 8gbs installed. My memory is a 2x2gb kit of xms3 1600mhz, and 2 other xms3 modules that are part of a 3x2gb kit. The motherboard is rated to run 16gbs of memory in a 4x4gb config. Why is my memory not usable?

 

[COLGeek]

Are you using a 32-bit or 64-bit version of Windows?

 

[WCB_01]

Are you using a 32-bit or 64-bit version of Windows?

64 bit windows 10

 

[DSzymborski]

Does the PC detect the proper amount of RAM when only the identical RAM sticks are installed? The first place to looks is your FrankenRAM situation; only RAM that's sold together as a kit is guaranteed to work together and it's a dice roll whether mixing-and-matching will work.

 

[WCB_01]

They're identical in terms of clock speed, timings, latency etc so I don't know where the incompatibility is coming from

 

[COLGeek]

They're identical in terms of clock speed, timings, latency etc so I don't know where the incompatibility is coming from

While that may be true, mixing memory can produce odd results. Is your motherboard BIOS the latest version? Have you reset your BIOS to its default state since installing the additional memory?

 

[WCB_01]

While that may be true, mixing memory can produce odd results. Is your motherboard BIOS the latest version? Have you reset your BIOS to its default state since installing the additional memory?

No, but I'll try it. Thanks for the advice

 

[DSzymborski]

They're identical in terms of clock speed, timings, latency etc so I don't know where the incompatibility is coming from

That doesn't necessarily mean anything. It's more likely similarly specced RAM will cooperate, but it's not a guarantee. Even RAM that is identical down to the model number will sometimes not get along (though this is more unusual).

In any case, whenever you have RAM that was not sold together, this is the first place to check. You can't rule "in" things if you don't start by ruling out things.