Not all 6 RAM modules detected on cold start

[Pada]

Hi guys,

I'm sitting with a funny thing with my 3x 2GB + 3x 1GB Corsair Dominator DDR3 1600MHz CL8 modules with my Asus P6T Deluxe v2 motherboard, where it will only detect 8GB on the first "cold start".
When I press reset or CTRL+ALT+DELETE, it then picks up all 9GB and works 100%. It would also detect all the RAM when I switch off the PC completely and switch it on again like within a few seconds.

When the BIOS detects 8GB, CPU-z can still show the info for all 6 modules when I'm in Windows.

I've already swapped the modules around and in different slots - and what happened when I swapped the 2GB & 1GB modules around, it would detect 7GB out of the 9GB.
So my best guess is that there is something wrong with the motherboard?! I'm already running the latest BIOS version.

 

[oldhat]

Seems to be a common problem - lots of possible solutions here: http://vip.asus.com/forum/view.aspx?id=20090919210224515&board_id=1&mod

 

[nakedpeanut]

I had this exact same problem, turned out to be faulty memory, I'd try testing with each set on it's own.

 

[Jola]

I also have a P6T deluxe, and have these issues from time to time.

This motherboard is definitely finicky with memory.

Apart from that really works well.

 

[PostmanPot]

Many 1366 mobos support 4GB DDR3 1.5v RAM. I'd suggest going for 3 x 4GB. Hate filling out all memory slots as there are often problems.

 

[Jola]

Many 1366 mobos support 4GB DDR3 1.5v RAM. I'd suggest going for 3 x 4GB. Hate filling out all memory slots as there are often problems.

I had problems even with that on this motherboard (mine is version 1).

I eventually got it stable with a weird combination (1*4; 2*2, set up as dual channel, two 4GB channels), and now I don't touch it.

 

[Pada]

Thanks guys. Much appreciated for the feedback.

I'll try to clean out my RAM modules and sockets and check the CPU socket for bent pins, etc.

For my gaming PC I don't mind having 8GB instead of 9GB, so I'm just going to stick with it like that. I've never had the PC being unstable due strange memory configurations. I only had an unstable PC due to too little vCore voltage when overclocking my CPU.
Unfortunately DDR3 1600 CL8 modules are rather expensive and I don't need more on my home PC than 8GB for the while being.

When I started up my PC just now, I had the same issue again and I had to turn off the PC before it detected all the RAM again.

And the IT Tech guy asks the user: have you turned it off and on again?

 

[sajunky]

If related to memory controller or/and addressing lines (as found in above link), it has to be traced from CPU to memory slots. It would be also dependent on specific slots not activating modules, or activating only smaller size (by example half of capacity). But you have tried many combination and you didn't pickup any specific pattern.
As you say that soft reset brings all memory, I think it is not sufficient power during startup causing some memory chips not initializing correctly. This is design problem of internal regulator not able to supply sufficient current to all modules during startup, combined with internal power good generation circuit (it should keep CPU on reset till all voltages are stable). If mobo is out of warranty, I would attempt to beef-up/replace caps in this section.
SPD (as reported by CPU-Z) has nothing to do with memory chips, it has separate power and comunicate over serial line. It is why is always present (even memory is not detected).