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  #1  
Old 10-03-2008, 06:29 AM
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Default Foxconn A79A-S and TWIN2X4096-8500C5DF?

On my system, the memory is detected and the system runs (broadly) correctly at 800MHz - but changing any of the BIOS memory settings ("MemClk Tristate C3/ALTVID", "Power Down Enable" set to "Chip" rather than "Channel", "Optimal Performance Mode" which enables use of the EPP SPD data, "Auto Tweak Performance") or setting the memory speed to 1066MHz causes the system to hang pre-POST even when the DIMM voltage is set to 2.112v (up from the default of 1.936v - this is with the first updated BIOS for this board: as shipped, the closest voltage was something like 2.15v).

Could someone from Corsair confirm whether the above BIOS settings should be expected to work, and provide any hints for why my system can't run its memory above 800MHz?

Last edited by Wired; 10-07-2008 at 03:38 PM. Reason: thread split
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  #2  
Old 10-03-2008, 04:04 PM
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Please test the modules one at a time with www.memtest.org to make sure one is not failing and I would set the tested settings manually.
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Old 10-03-2008, 04:12 PM
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Sure - will do... but in the meantime please could you post whether any of the above BIOS settings (and I'm thinking about the Tristate and Power Down options here - should chip-level power control work?) are specifically known to be good or bad when used on conjunction with the Dominator DDR2 memory modules?

Last edited by srcshelton; 10-03-2008 at 04:14 PM.
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Old 10-03-2008, 04:38 PM
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Actually, it's probably worth mentioning that whilst I've been typing this, the machine has been rebuilding a Linux installation from source - and so the modules definitely work successfully at 800MHz and under load.

In addition, I did run memtest86+ on the machine a couple of weeks ago before I went away for a break, and that succeeded (again at 800MHz).

Once the compilation has finished I'll re-run memtest86+ to confirm, but assuming that no problem occur, what can I do next?

To recap, the machine won't even POST at more than 800MHz - so its not just a case of instability.

I think I read somewhere on this forum that increasing one of the other voltages may help - is this advisable for AMD boards (it may have been a suggestion to increase the North Bridge voltage on Intel boards)? If so, what voltages should be upped in addition to the DIMM voltage? Should the memory be running at 2.1v or 2.15v, and is that last 0.05v likely to make any difference?
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  #5  
Old 10-03-2008, 05:16 PM
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That sounds like a MB BIOS problem, and I would check with the MB maker for a newer BIOS but to be sure you can over clock the CPU to get the higher memory frequency and see if it will pass www.memtest.org.
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  #6  
Old 10-03-2008, 05:47 PM
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The BIOS is definitely the latest - I upgraded yesterday. The problem is that at 1066MHz, it's not a case of memtest86 failing due to instability - it won't even POST and requires a CMOS reset to even enter BIOS setup! :(
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Old 10-03-2008, 06:10 PM
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Like I said please set the memory frequency at DDR800 and over clock the CPU to get the memory frequency higher but do it a few MHz at a time up to 266 MHz that will set the memory to DDR1066.
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Old 10-06-2008, 06:34 AM
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I've now tried this, and using the AMD OverDrive utility, the board/CPU/RAM combo can overclock to a massive 205MHz CPU/memory clock :(

I did try increasing the voltages and applying a 266MHz clock whilst reducing the processor multiplier and HT ratio to keep things at about the same levels (which would have resulted in a 266MHz memory clock, each 2.5GHz core running at 2.48GHz, and an HT bus of 2.1GHz rather than 2Ghz), this this (predictably) froze the machine.

Serious question: Am I mistaken to expect a CPU with a memory controller compatible with a 1066MHz bus, 1066MHz-capable memory, and a modern motherboard to just-work? Surely, this should all be auto-detected by the BIOS and it shouldn't be necessary to (attempt to) overclock different parts of the system?

I'm most displeased right now with the performance of the Foxconn board - do other boards (I'm thinking of the Asus M3A79-T) work out-of-the-box at 1066MHz, or at least out-of-the-box with a vDIMM increase?
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Old 10-06-2008, 03:59 PM
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Yes but that is a BIOS issue and the BIOS may not be fully matured on that MB as of yet.
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  #10  
Old 10-07-2008, 04:53 AM
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I read on a different forum today that Asus' documentation states that 1066MHz operation is only supported for a single DIMM, and that as soon as a second is added, everything drops back to 800MHz.

Is this be, after all, a CPU/chipset limitation?
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  #11  
Old 10-07-2008, 01:59 PM
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Yes it could be, where did you see that limitation information? Can you post a link to it?
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Old 10-07-2008, 02:47 PM
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The message I saw was:

http://forums.amd.com/forum/messagev...hreadid=100918

However, the only similar reference I can find on ASUS' site is:

"* DDR2 1066 is supported by some of the AM2+ CPUs only. Refer to www.asus.com for the supported CPU models."

... which presumably does little but rule out Semprons.
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Old 10-07-2008, 03:16 PM
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Quote:
I'm most displeased right now with the performance of the Foxconn board - do other boards (I'm thinking of the Asus M3A79-T) work out-of-the-box at 1066MHz, or at least out-of-the-box with a vDIMM increase?



i dont know much about AMD, but doesnt it look like this board can handle 2 modules at 1066?


QVL list
Attached Images
File Type: jpg asus amd.JPG (348.4 KB, 962 views)

Last edited by 007bont; 10-07-2008 at 03:23 PM.
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  #14  
Old 10-07-2008, 03:34 PM
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Ah, that's the QVL list I was looking for. I assume that the blue "V"s mean 'verified', or similar. Note that the final page of the PDF document define what columns A, B, and C actually denote.

The document seems to suggest that on the Asus board two DIMMs in two channels at 1066MHz is supported, but that 4 DIMMs would cause the speeds to drop back to 800MHz.

I have two DIMMs in two channels on the A79A-S, yet the system still completely fails with any speed above 800MHz.
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  #15  
Old 10-07-2008, 04:22 PM
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Yes that shows it will support 2 modules at DDR1066 but if you install 4 modules DDR800 or DDR667 would be suggested. You only have one set of modules correct? And you have tested them one module at a time?
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