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P55-UD3L - Memory Issue

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Anonymous
a b V Motherboard
August 19, 2010 8:46:34 AM

Okay, so first off let me say that I did read the GIGABYTE guide, and I found it very useful. But most of what it suggested I have already tried. My problem has actually been on-going since I first got the motherboard (GIGABYTE-P55-UD3L, rev 1.0), and GIGABYTE tech support had given me such a runaround that I gave up for the time being (that was a few months ago).

The issue I'm having is that my motherboard won't recognize all the RAM. I will go ahead and say that I have thoroughly "memtested" all the sticks using the boot-up disc. Even ran a 5-hour-long depth test. A few months ago, when I got the board, I started off with 4GB DDR3 1600MHz (2x2GB)...got it stable enough to make me satisfied for the moment. But I knew that once I added 2 more modules, problems would pop up. And that's exactly what happened.

I purchased two identical 4GB (2 x 2GB) dual-channel kits since I have 4 DIMMs - G.SKILL DDR3-1600 PC3-12800 (F3-12800CL9D-4GBNQ)
My motherboard is as mentioned - GIGABYTE-P55-UD3L, rev 1.0 and my processor is an Intel Core i5-750
BIOS revision - F7 (latest)
Other specs - APOWER 750w PSU and ATI HD Radeon 5830 GPU

When I installed all the sticks, I booted up into windows and got the "8GB (3.99 usable)" message in the computer properties.
BIOS stated that 4096MB was installed.

I immediately attacked Google for information and have since tried things like resetting the CMOS, searching for bent pins and reseating the CPU (none found), rearranging the RAM modules etc. Typically, I have CPU overclocked to 2.72GHz or 3GHz and RAM to 1500MHz or 1600MHz, but for my troubleshooting I tried both variations of overclocked and default settings. So I think it's safe to say that I've tried just about everything. I've heard others say to enable/disable "memory mapping," but as far as I know that option is not available on this motherboard.

After awhile I suspected it was either a defective slot (which was my prediction several months ago, when GIGABYTE assumed it was my RAM) or the stick itself. I proceeded to install and test each stick one by one in the first slot, then proceeded to fill up subsequent slots. The results surprised me--

I finally managed to get 6GB to show up by filling the first three slots farthest from the CPU (DDR3_3, DDR3_4, and DDR3_1). I thought that DDR3_2 was defective but then I was able to fill DDR3_3, DDR3_1, and DDR3_2, leaving the stick out of DDR3_4. This indicates that Channel B (DDR3_4 and DDR3_2) must have some sort of issue. I can put whatever sticks I want in Channel A (DDR3_3 and DDR3_1) without any problemos. And like I said, I can put one module in Channel B, but when I put both together then the Channel B RAM doesn't show up at all. If I fill Channel B only and put nothing in Channel A, then the computer won't POST and has boot-loops.

Some guidance on how to resolve this issue would be helpful.

Thanks!

More about : p55 ud3l memory issue

a b V Motherboard
August 19, 2010 10:30:03 AM

Channel B may not work as you may need to full up channel A full of RAM before channel B. This is strange.

Try going to msconfig, the 'Boot' tab, then 'Advanced', and there check the box 'Maximum memory' and type in 6144.
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a c 177 V Motherboard
August 19, 2010 2:13:14 PM

The RAM parameters in both the SPD and XMP on the DIMMs are designed for use in one DIMM per channel situations; for use with two DIMMs per channel, some changes to the RAM setup are usually required: you need to 'bump' your Vdimm a couple hundreths of a volt, you need to bump your QPI/Vtt to within a max of a half volt of your Vdimm (and I like to keep the difference around .35V, just to be sure), you need to raise your tRFC timing 10-15% higher than it's currently at, and you need to make sure that the 'command rate' is set to '2', '2T', or '2N' - whichever way your board shows it...
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Anonymous
a b V Motherboard
August 19, 2010 6:28:58 PM

Lmeow said:
Channel B may not work as you may need to full up channel A full of RAM before channel B. This is strange.

Try going to msconfig, the 'Boot' tab, then 'Advanced', and there check the box 'Maximum memory' and type in 6144.

I only have four slots, two for each channel. Currently, when I fill all four slots with 2GB each, only 4GB total shows up. If I fill three out of the four slots, 6GB shows up. I have already checked the boot tab on msconfig, and the box is not checked, but I will see if I can type in 8GB (8192) to get the full 8GB to show up.
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Anonymous
a b V Motherboard
August 19, 2010 6:30:14 PM

bilbat said:
The RAM parameters in both the SPD and XMP on the DIMMs are designed for use in one DIMM per channel situations; for use with two DIMMs per channel, some changes to the RAM setup are usually required: you need to 'bump' your Vdimm a couple hundreths of a volt, you need to bump your QPI/Vtt to within a max of a half volt of your Vdimm (and I like to keep the difference around .35V, just to be sure), you need to raise your tRFC timing 10-15% higher than it's currently at, and you need to make sure that the 'command rate' is set to '2', '2T', or '2N' - whichever way your board shows it...

I've already tried messing with the voltages and it didn't work, but I will follow your suggestions right now.
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Anonymous
a b V Motherboard
August 19, 2010 6:47:57 PM

Okay, I tried everything yall suggested but nothing worked. Guess my next step is RMA. Thanks anyway
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