16GB of missing memory

[Prestones]

I have a Windows 7 Pro SP1 x64 machine (Build 7601) with an Asus P6T Deluxe motherboard. When I originally built it in 2009, I had an i7 920 cpu and 4GB Corsair DDR3 1333 (2x2GB TR3X6G1333C9) with BIOS Revision 0804.

About 4 years later, things began slowing down a bit, so I added more RAM to bring the total to 12 GB, using more Corsair DDR3 1333 memory (now 6x2GB TR3X6G1333C9). All was well again - for a while.

The computer began slowing once again after another 3 or 4 years, so I bumped the RAM to 24GB with 3x8GB Memory PC3-12800 DDR3 1600 in the orange memory slots (DMM_A1, DMM_B1, DMM_C1 - Channel A, Channel B, and Channel C, respectively), per the manual directions for the Asus P6T Deluxe. Also according to the manual, "... DDR3 -1600 are supported for one DIMM per channel only." The extra memory made for another increase in the computer's speed, and I was a happy camper once again.

Moving forward to the 9 year mark, I began doing a bit of CAD work, inclusive of some related video generation. As you may have guessed, things slowed down again, so I pulled the i7 920 and replaced it with an i7 990x. Unfortunately, the machine refused to boot, and I went back to the i7 920 long enough to install the most recent BIOS (version 2209). Voila - the machine booted now with the i7 980x installed. I haven't overclocked anything - the i7 980x and DDR3 1600 are running stock.

Unfortunately, now it only shows 8GB of DDR3 - I'm missing the other 16GB. It doesn't seem the memory would be bad (since it was all there when BIOS 0804 was running the show), but I can't test all 24GB of memory since the machine doesn't recognize it's installed. I've tried re-arranging / re-seating the 3 8GB DDR3 memory cards - to no avail. I'd prefer not to keep swapping the i7 920 and the i7 980x too many times for fear of bending a pin.

Having said all of the above, can you suggest any scathingly brilliant ideas - or just pass along a clue as to how to find the missing memory and put it back to work?

Many thanks!

 

[Sysnative Windows Update]

Hi, what's your VQPI setting set to?

 

[Prestones]

Here I am, darkening your doorway again. I had two problems with my computer, and you drew the short straw - twice! <chuckle>

I had to beat Google about the head and shoulders to find out what the VQPI setting was, and finally found reference to it on an Italian website - thanks to Google's ability to translate. Hopefully the screen shots of the AI Tweaker tab in BIOS contains the bits of interest to you. If not, please direct me to the correct location.

 

[Sysnative Windows Update]

Try changing the QPI voltage to 1.35 V and saving that.

 

[Prestones]

I changed the QPI/DRAM Core Voltage setting to 1.35, saved it (F10), and went through a reboot. Sysinfo still reports a total of 8,183MB of physical memory. Nuts.

While I was rummaging around in BIOS, I took a look at the DRAM settings on the AI Tweaker tab, and grabbed the two screen shots below. If the DRAM Timing Control is showing information for the 3 memory sticks (1st Information through 3rd Information), do the varying stats for the sticks affect their performance or lack thereof?

Apologies for the pictures - they're a little fuzzier than I thought.

 

[Sysnative Windows Update]

As far as I know, latency and timings only affect the speed as such. Is the BIOS seeing all the RAM?

 

[Wrench97]

If the QPI voltage change does not help try booting with one stick at a time installed, swapping slots to see if all are working.
I suspect you may be missing 2 of the memory channels on the new CPU.

 

[Sysnative Windows Update]

That'd 've been my next suggestion, but I'd like to eliminate the obvious first :)

 

[Prestones]

The BIOS reports 8,184MB of physical memory, so the other two sticks are hidden from view there too.

I'm off to play with the installed memory - one stick at a time. Stay tuned.

 

[Sysnative Windows Update]

Try Wrench's suggestion about swapping sticks and trying one at a time.

 

[Prestones]

Here's what I found -

Single memory stick attempts -

Only Stick 1 in:
DIMM A_1
Normal boot; BIOS showed 8,184MB of DDR3 1600
DIMM B_1 no BIOS beep; no boot possible
DIMM C_1 no BIOS beep; no boot possible

Only Stick 2 in:
DIMM A_1
Boot #1 BIOS message: Overclocking failed! I pressed F1 to get into BIOS Setup and restored vQPI to Auto (previously set at 1.35 volts)
Boot #2 BIOS message: Overclocking failed! I pressed F1 to get into BIOS Setup, then pressed Escape to continue booting.
BIOS showed 8,184MB physical memory as DDR3 1333 (not DDR3 1600). Login screen never appeared so I shut the computer down at the power switch.
Boot #3 Same as #2 (still showing 8,184MB of DDR3 1333), but was able to login.
The system didn't seem normal; Malwarebytes Real-Time protection was off and I couldn't re-start it. I shut down the computer normally.
Boot #4 Same as #3 (still showing 8,184MB of DDR3 1333). Once again, the system didn't seem normal. I had the same issue with Malwarebytes Real-Time protection.
DIMM B_1 no BIOS beep; no boot possible
DIMM C_1 no BIOS beep; no boot possible

Only Stick 3 in:
DIMM A_1
Normal boot, with BIOS showing 8,184MB physical memory as DDR3 1600. Note: vQPI remained set to Auto.
Malwarebytes Real-Time protection was still off, so I removed the program, then rebooted and reinstalled it to fix the issue.
DIMM B_1 no BIOS beep; no boot possible
DIMM C_1 no BIOS beep; no boot possible

Stick 1 and Stick 2 in:
DIMM A_1 and DIMM B_1, respectively
Boot #1 BIOS message: Overclocking failed! I pressed F1 to get into BIOS Setup, then pressed Escape to continue booting.
BIOS showed ?? memory as DDR3 ?? (missed the message - oops!). Malwarebytes Real-Time protection was off again; I was unable to re-start it. Removed Malwarebytes and shut down the computer normally.
Boot #2 Normal boot sequence - no "Overclocking failed!" message. I reinstalled Malwarebytes - it functioned normally again.
BIOS shows 8,184MB of physical memory as DDR3 1600.
Boot #3 Normal boot sequence - no "Overclocking failed!" message, and no problem with Malwarebytes.
BIOS shows 8,184MB of physical memory as DDR3 1600.
DIMM A_1 and DIMM C_1, respectively
Normal boot sequence; BIOS shows 8,184MB of physical memory as DDR3 1600.

Stick 1 and Stick 3 in:
DIMM A_1 and DIMM B_1, respectively
Normal boot sequence; BIOS shows 8,184MB of physical memory as DDR3 1600.
DIMM A_1 and DIMM C_1, respectively
Normal boot sequence; BIOS shows 8,184MB of physical memory as DDR3 1600.

Old 2x6 2GB Corsair DDR3 sticks in all 6 motherboard slots:
Normal boot sequence; BIOS shows 2048MB of physical memory as DDR3 1333

 

[Wrench97]

Swap the other CPU back in I believe you're either going to have a bad CPU or damaged contacts in the socket.
Did you buy this CPU new or used?

 

[Prestones]

Into the belly of the beast, eh? I'll take a look at the contacts on the board while I'm changing the CPU to see if any problems jump out at me.

I use the computer to augment our retirement income, so I'll probably be about a week getting back to you on the results of the inspection / swap. I want to get the work on deck cleared away first, on the off chance that I tank the machine for more than a day.

 

[Prestones]

Apologies - I was thinking about the task at hand and neglected to answer your question. I bought the CPU used - new would have been above my pay grade!

 

[Wrench97]

Possibility that the previous owner fried the cpu over-volting a overclock.

 

[Prestones]

Good grief! Over two weeks have passed, and I'm still trying to clear a day or two to take the computer down.

I haven't dropped off the face of the earth. I just have the minor issue of finishing my taxes before I pull the beast apart. Thanks for your patience!

 

[Prestones]

When I pulled the motherboard and gave it a good looking at, I found the following:

Apologies for the odd picture. I had to hold my phone at an angle, and the focus of the macro lense was all over the place as a result. There's a bent pin in the middle of the picture - so I guess this one's on me. I must have been a little careless when swapping the CPUs.

I put the system back together (still with the 990X in it) and booted it back up. It initially indicated 24GB at boot, and sent me off to BIOS because it thought I had a new CPU installed. When I rebooted a second time, only 16GB were showing - so perhaps I have another gremlin among the CPU pins. I did spend 45 min or so checking out all the pins' alignment in both directions. To the extent I was able, I also checked out the height of the pins to see if any were too low to make good contact.

Unless you have any other suggestions, it looks like I may have another trip down under the CPU in in my future to give the pins a more intensive look - or to swap the 920 back in and see if the problem is in the 990X.

 

[Wrench97]

Starting on page 40 of this Intel PDF file are the pinout grids of which pin does what > https://www.intel.com/content/dam/w...top-processor-series-32nm-datasheet-vol-1.pdf

 

[Prestones]

Thanks much for your guidance Wrench! It'll take me a while to understand how to interpret the pdf you linked, but I'll begin poking at it.

Now I know the likely culprits I can use swapping and inspection as you've suggested to find the remaining 8GB in a bad memory card, a bent pin, or a toasty CPU.

Much appreciated!