P9X79 only sees 20GB of 32GB (2400MHz) RAM @ 2400MHz?

oxf77

oxf77

oxf77

Associate
Joined
15 Nov 2011
Posts
169
CPU: i7 4820K
Mobo: P9X79
Memory: 32GB of Kingston Hyper X @ 2400MHz

When I set the speed of the memory to 2400MHz (or 2133) only 20GB is seen by the BIOS (and Windows). I have to drop the speed to 1866 for all 32GB to be seen.

Why is this?? The memory I bought it rated at 2400MHz?? Is there any way around this?
 
I would try the sticks one by one at 2400MHz and 2133MHz and see if any fail to boot the system and if they all boot try them again one by one and run memtest on each stick at the speeds you need them to run at. Also make sure you have the latest BIOS for your motherboard.
 
more slots filled = more stress.

Some of my old boards (asus extreme's) while stating they support up to 2400 or 3200 or w/e can only run it when its filling one set of slots, fill all and the max speed is lower.

But as above, check each stick to confirm its not just the ram.
 
Purgatory said:
I would try the sticks one by one at 2400MHz and 2133MHz and see if any fail to boot the system and if they all boot try them again one by one and run memtest on each stick at the speeds you need them to run at. Also make sure you have the latest BIOS for your motherboard.
Click to expand...
Ive got the latest BIOS. when I ran CPU-z it said each of the memory sticks was running was 668MHz in Quad channel....

(I've got another thread open because I have been trying to overclock my CPU but the frequency doesn't seem to shift from 3.7GHz. May be I have actually overclocked something, hence 668 x 4?)
 
Last edited:
If it wasn't seeing a stick it would show 24GB not 20GB, is this a limit with some version of Windows or something?

Edit: didn't read lol.
 
Last edited:
I agree it seems imc related. The imc is struggling to relate the full 32gb when all the slots are populated at said speed. Seeing as it's actually correcting when spec'd down points to this.
I had a similar issue years back with the i7 920 populating all slots. It put so much strain on the Imc and board it reduced my over clock to 3.7ghz from 4ghz and had to use 12gb @ 1450mhz rather than 6gb 1866ghz. I tried everything but with full slot population just stressed it all too much.

Your May be just needing more voltage in certain places though. What's your CPU clock ?
 
McstylisT said:
I agree it seems imc related. The imc is struggling to relate the full 32gb when all the slots are populated at said speed. Seeing as it's actually correcting when spec'd down points to this.
I had a similar issue years back with the i7 920 populating all slots. It put so much strain on the Imc and board it reduced my over clock to 3.7ghz from 4ghz and had to use 12gb @ 1450mhz rather than 6gb 1866ghz. I tried everything but with full slot population just stressed it all too much.

Your May be just needing more voltage in certain places though. What's your CPU clock ?
Click to expand...
Ok update, managed to get my CPU overclocked. i7 4820K running @4.7GHz.

Here's a question though, in CPU-z it says my memory is running in quad channel, but it says the DRAM frequency is 1333MHz?? Now I always thought in CPU-z you take the DRAM freq and multiply it by the channel number to get the frequency. So Dual-channel 1600 shows up in CPU-z as "dual" and 800MHz. If my Kingston memory is rated as 2400MHz, then it can't be 1333 x 4?!?! It looks more like a dual-channel value, except CPU-Z says "quad". Can someone help explain this?

Btw, as of now, Windows says 28GB, but CPU-z says "32 GBytes" :p So does this mean a windows (Ive got Windows 7 pro 64 bit) bug?

EDIT: I disabled my page file capability, restarted the machine and now Windows recognises 32GB!?
EDIT 2: regarding the 1333MHz in CPU-Z it seems like thats expected. See this:

http://www.kitguru.net/wp-content/uploads/2011/11/64gb-2600MHz.jpg

Now why does it show half of the quoted frequency and not a quarter for quad-channel?!
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom