ozzyau Posted October 23, 2010 Share Posted October 23, 2010 Hi all, I recently upgraded my core components. I booted up, loaded the 'optimised defaults' and ran memtest for 1 pass as an initial check - everything came back all good, all RAM detected - except I noticed it reportedly running at 1066 MHz 7-7-7-20. This was confirmed in the BIOS - it had the SPD frequency value and current running value, both of which were reading 1066MHz. In the Memtest 4.10, it showed: Slot 0 : 4096 MB PC3-8500 - CORSAIR CMX8GX3M2A1333C9 Slot 1 : 4096 MB PC3-8500 - CORSAIR CMX8GX3M2A1333C9 I then flashed the BIOS to the latest F13, resetting the CMOS, and loading optimised defaults again. However, this resulted in no change in the detection above. If I change the system memory multiplier from 8 to 10, the memory does run at DDR3-1333 successfully (no change to voltage : 1.50V). My question is, is this a Gigabyte motherboard issue in detecting the correct SPD? Or is the SPD correct and the module is actually DDR3-1066 (PC3-8500) that is capable of 1333 @ 1.5V (akin to how some DDR3-1600 kits default to DDR3-1333 @ 1.5V, but are capable of DDR3-1600 @ 1.65V?) I'm not really worried, as it has tested 12 hours of memtest so far at DDR3-1333, which I'm pretty happy with considering it's 1.50V and the memory controller is having to deal with 8GB in two DIMMs. Thanks for any feedback! Link to comment Share on other sites More sharing options...
Synthohol Posted October 23, 2010 Share Posted October 23, 2010 post a screenshot of the SPD tab in CPU-z. 1066 may just be the JEDEC spec (default) and 1333 is the overclocking profile. if the multi is at 10 and it runs at 1333 just leave it there. Link to comment Share on other sites More sharing options...
ozzyau Posted October 23, 2010 Author Share Posted October 23, 2010 Hi Synthohol, That was next on my list, and i'm just installing windows now. Yes, exactly what I was thinking, that 1066 was the 'actual' speed and 1333 was the 'tested to'. However, given the voltages are the same, I don't know why this would be the case; surely Corsair would have just used 1333 spec as default. I'll get that CPU memory tab info shortly to find out.. Cheers. Here it is: Well, the above seems to be the case, though I would have thought JEDEC #4 would have been 667MHz - where does 685MHz come from?! and why does JEDEC #4 run on 1.50V but the XMP profile, which runs even slower at (the correct) 667MHz, but needs 1.60V? Link to comment Share on other sites More sharing options...
trackrat Posted October 23, 2010 Share Posted October 23, 2010 The Corsair CMX8GX3M2A1333C9 has a voltage rating from 1.5-1.65 V. Your CPU can run RAM at 1066/1333 MHz. The SPD settings are typically for 1066 MHz. @ 1.5V. The 1333 MHz. "speed rating" of the RAM is 1333 MHz. @ 1.65 V. The XMP profile is a best guess BIOS settings and may or may not work or be the best BIOS settings. Any JEDEC referenced settings will show the DDR3 industry standard of 1.5 V. Your CPU is not guaranteed to run stable at any RAM frequency above 1333 MHz. so it's a cut and try deal if you want to run faster. http://www.newegg.com/Product/Product.aspx?Item=N82E16820145315 Link to comment Share on other sites More sharing options...
Synthohol Posted October 24, 2010 Share Posted October 24, 2010 I would have thought JEDEC #4 would have been 667MHz 1066 i believe is the max JEDEC speed spec, it has nothing to do with the chip maker :): the XMP profile in your bios settings would be your best bet, it should even set the correct voltage. you can also set it manually too with the timings and voltage typed on the stick. good luck!! Link to comment Share on other sites More sharing options...
ozzyau Posted October 24, 2010 Author Share Posted October 24, 2010 The Corsair CMX8GX3M2A1333C9 has a voltage rating from 1.5-1.65 V. Your CPU can run RAM at 1066/1333 MHz. The SPD settings are typically for 1066 MHz. @ 1.5V. The 1333 MHz. "speed rating" of the RAM is 1333 MHz. @ 1.65 V. The XMP profile is a best guess BIOS settings and may or may not work or be the best BIOS settings. Any JEDEC referenced settings will show the DDR3 industry standard of 1.5 V. Your CPU is not guaranteed to run stable at any RAM frequency above 1333 MHz. so it's a cut and try deal if you want to run faster. http://www.newegg.com/Product/Product.aspx?Item=N82E16820145315 In addendum to that, the sticker voltage is the true/tested voltage right? i.e. mine has, like that newegg picture, voltage of 1.50V - 1333MHz 9-9-9-24. Is the sticker voltage the maximum for the DIMM or simply just what the DIMM was tested at to obtain the speed? 1066 i believe is the max JEDEC speed spec, it has nothing to do with the chip maker :): the XMP profile in your bios settings would be your best bet, it should even set the correct voltage. you can also set it manually too with the timings and voltage typed on the stick. good luck!! I've read some bad things about the XMP profile as it overclocks other things right? I'm not really into overclocking per se, and don't mind stock performance. My understanding (and correct me if it's wrong) from what the CPUz SPD tab reports, is that because JEDEC #4 profile is basically a tad faster (at 685MHz) than what i want to run (667MHz / DDR3-1333), and since the voltage is 1.50V for both, then I need not run the XMP setting. Simply changing the system memory multiplier from auto to 10 whilst leaving the timings set to Auto, seems to have achieved what the label reports. after 16 hours of memtest and an hour last night of linpack/linx x64, I think it's stable. Link to comment Share on other sites More sharing options...
trackrat Posted October 24, 2010 Share Posted October 24, 2010 The label on the memory is what you need to use for voltage to run the rated speed for the RAM. I'm not aware of Corsair publishing specific maximum voltages for their RAM. It's worth noting that some Intel mobos/CPUs do not like high RAM voltages. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.