Overstressing the memory controller. Best overlocks are achieved with 2 memory modules. But yeah, X38/X48 most likely won't recognize 8Gb modules. Even some later CPUs from i5/i7 families had issues with that. Also keep in mind that all 8Gb modules had craptastic sub timings to work properly.

The Serpent Rider wrote on 2024-06-17, 17:44:

Best overlocks

This isn't for overclocking. I'm running everything at stock speeds (maybe except RAM) because it's all passively cooled.

moog wrote on 2024-06-18, 05:16:

The Serpent Rider wrote on 2024-06-17, 17:44:

Best overlocks

This isn't for overclocking. I'm running everything at stock speeds (maybe except RAM) because it's all passively cooled.

Never heard of 32Gb on a 775 motherboard, my Rampage X48 has issues with 16Gb and it took me a while to find 4 4Gb modules that allowed that board to post with 16gb. Not even sure 32Gb is possible even with the ram underlocked and undervolted let alone with ram at stock settings.

Even with the 16Gb the system is hardly stable, 16Gb is honestly pushing the northbridge memory controller pretty damn hard, X48 works perfectly well with 8Gb and can hit some silly memory speeds with 2Gb or 4Gb, I have a 790i ASUS board that will also work with 16Gb and is more stable with that ram than the X48 is.

I have a fair amount of experience with these boards and 32Gb is just someone pissing in the wind, the Northbridge already gets crazy hot with 16Gb.

If I was to go beyond 16Gb I would be firing up a 1366 setup that has the capacity to handle 48Gb on the higher end boards or 24Gb on normal boards.

I had 16GB running on Asus P5E3 Pro, no problems, everything smooth. Of course you need Dual-rank (16-chip) DDR3 sticks for this.

More than 16 GB is not possible I think.

havli wrote on 2024-06-18, 06:03:

I had 16GB running on Asus P5E3 Pro, no problems, everything smooth. Of course you need Dual-rank (16-chip) DDR3 sticks for this.

More than 16 GB is not possible I think.

Yeah its only specific modules that will work okish, it really depends on how good the Northbridge is, like CPUs not all are made the same, like the 790i running just fine with 16Gb but the X48 struggling. Even with 16Gb working ok you are not going to be doing much overclocking or being able to run fast speeds on it. 1066 or 1333 should be ok at 16Gb though but 1600 might be a push.

Looking at my personal testing and benchmarking notes I haven’t recorded ever pushing a DDR3 X48 or earlier system past 8GB (2 * 4GB, probably of Trident X, it’s my go to for DDR3 and really good stuff IMHO). I would have been prioritising speed over capacity, and as mentioned, those early DDR3 memory controllers are fussy. As always, it takes time for a new RAM platform to mature, and the end of s775 happened to catch the very start of DDR3. At the time a big selling point for DDR3 was for overclockers who were being limited by DDR2 when pushing the FSB.

I can’t see why 4 * 4GB for 16GB total wouldn’t work, though you’ll need to compromise on speed and timings. Higher density sticks would be a try it and see, but I wouldn’t count on it.

Trashbytes wrote on 2024-06-18, 07:07:

havli wrote on 2024-06-18, 06:03:

I had 16GB running on Asus P5E3 Pro, no problems, everything smooth. Of course you need Dual-rank (16-chip) DDR3 sticks for this.

More than 16 GB is not possible I think.

Yeah its only specific modules that will work okish, it really depends on how good the Northbridge is, like CPUs not all are made the same, like the 790i running just fine with 16Gb but the X48 struggling. Even with 16Gb working ok you are not going to be doing much overclocking or being able to run fast speeds on it. 1066 or 1333 should be ok at 16Gb though but 1600 might be a push.

I've just gotten 2 sets of F3-2400C11D-8GXM and will be testing them out. As for overclocking - if there's any lesson that the PS3 had to teach, is that 256MB of ridiculously fast RAM is infinitely worse than ridiculous amount of much slower RAM. I remember running Linux on PS3 and it was swapping all the time thus killing all performance in all applications more sophisticated than md5 bruteforcing.

Also, I've tested the board with various 8GB memories - none of which worked. POST would get stuck on code 00 or 02, depending on the RAM stick.

Update: F3-2400C11D-8GXM is a bust, these modules are single rank. What's worse, G.Skill doesn't say which modules are dual rank or single rank. I'll email their sales dept. and we'll see what comes of that.

I'm back with news.
After many weeks and many tests, here's a shortlist of GSkill RAMs (chosen due to best timings and speeds) that will do the trick:
- F3-10666CL9D-8GBNT (I have selected this one)
- F3-10666CL9S-4GBNT
- F3-10600CL9D-8GBNT
- F3-10600CL9S-4GBNT

Furthermore, some motherboards like the Gigabyte GA-X48T-DQ6 may deliver insufficient amount of power to the 64 memory chips. I've run memtest86+ 6.20 and have found that this combination of hardware that I have, will exhibit the following behavior:
- when at any speed from 1333MHz to 800MHz, and any combination of northbridge voltages, the memories will exhibit errors in tests 6 (inversion assignment) and 9 (random number assignment) with a very predictable pattern of failures
- when speed was set back to stock (1333MHz) and northbridge voltage was set back to stock, the same happened, exactly the same pattern
- but when I started adding voltage to the RAMs, the situation has started to gradually improve from at least 100 errors per pass (stock voltage) to 1 error per pass (+0.15V)
- when at +0.2V, the system started exhibiting erratic behavior like random hangups and resets
- the situation was not helped by adding 0.1V to northbirdge voltage

The pattern of failures is that every address where the failure occurs, you can binary and it by 0x00000000b0000598 and it will return exactly 0x00000000b0000598. In the 16GB present, this typically occurs somewhere after 2nd, 6th, 10th and 14th GB, but before the next gigabyte. And it's always the same 1 bit flipped - 0x0000010000000000.

Will keep you all tuned for when I arrive at a stable configuration

Regular Samsung 4Gb 1600MHz modules, which can also work on 1.35V, will do just fine. They are better than any early overclocking modules.

After much time, I have defeated the issue. In order to achieve perfect stability on X48 with 16GB RAM, I needed to turn on Load Line Calibration.

moog wrote on 2024-09-24, 21:34:

After much time, I have defeated the issue. In order to achieve perfect stability on X48 with 16GB RAM, I needed to turn on Load Line Calibration.

Its odd that LLC has any affect on the ram stability since the memory controller isn't part of the CPU and LLC simply stabilises the Vcore voltages. Perhaps a big vdroop happens with 16Gb and no LLC causing the CPU to have issues communicating with the memory controller on the Northbridge.

Very strange, perhaps its also helping to stabilise north bridge voltages, not 100% sure how LLC worked on them older motherboards but it would be worth investigating if the voltages to the northbridge are being affected.

But if it works for you then great it may also work for others and perhaps even with 790i too !!