tallguy2682 Posted October 9, 2013 Share Posted October 9, 2013 I have a MSI Z77A-G41 motherboard, i7 3770K and 2 4GB CMX8GX3M2A1600C9 and just bought today an 8GB stick of Crucial ram BLS8G3D169Ds316FE. I went to configure the ram and check options and noticed that the Corsair ram is running at 1333. I have read that enabling XMP makes the ram run at its intended speed (side note - this makes no sense that you would have to enable XMP to 'force' ram to run at its designed speed) but the XMP option is greyed out currently for me. There is an option to select DRAM speed and I have selected it to be 1600. When i run CPU-Z and go to the SPD tab, the Crucial ram (which I might add when in the machine by itself doesnt need to have XMP enabled to operate at 1600) is operating at 800 MHZ but the two sticks of Corsair are operating at a max bandwith of 667 (x2 which makes the 1333). Why is it reverting back to 1333? Also the timings have changed on the memory tab. They are now 11-11-11-29, when all the ram that I have operates at 9-9-9-24. I can post any screenshots if you just let me know what you need. Thanks! Link to comment Share on other sites More sharing options...
Yellowbeard Posted October 9, 2013 Share Posted October 9, 2013 Post your CPU-Z screenshots. Also, keep in mind that the XMP option is not there to make the memory run at its rated speed. It overclocks the memory controller. Also, when you mix and match memory like you have, it's impossible to predict how the motherboard and CPU will react. Link to comment Share on other sites More sharing options...
tallguy2682 Posted October 9, 2013 Author Share Posted October 9, 2013 Thanks Yellowbeard, I will post the CPU-Z screenshots tonight when I get home. So if XMP overclocks the memory controller, I guess my question should be why is it necessary to overclock anything if the memory is supposed to operate at 1600 normally? When I have just the Corsair in the mobo it runs at 667 mhz without any tweaking of bios i.e. enabling XMP. Link to comment Share on other sites More sharing options...
Yellowbeard Posted October 9, 2013 Share Posted October 9, 2013 If you want to run memory at 1600, this means the memory controller has to be overclocked from it's stock frequency. Link to comment Share on other sites More sharing options...
peanutz94 Posted October 9, 2013 Share Posted October 9, 2013 When I have just the Corsair in the mobo it runs at 667 mhz without any tweaking of bios i.e. enabling XMP. Memory when first inserted into your MB will default to it's slowest speed to make sure the machine uses a fail safe setting to boot correctly until otherwise changed in the BIOS. In your case it's 1333mhz is the default value. Hence the 667mhz your seeing. DDR stands for double data rate. So you would take 667mhz x 2 for 1333mhz. When you enable the XMP profile in your BIOS it will overclock the memory controller,changing buss speed and timings as well as voltage if necessary, allowing the memory to run at 1600mhz. Or 800mhz in CPUz. Link to comment Share on other sites More sharing options...
tallguy2682 Posted October 10, 2013 Author Share Posted October 10, 2013 Thanks Peanutz and Yellowbeard. I knew about the multiple of 667 I guess the thing I didnt realize was that the memory had a slowest speed of 1333, i just figured that since i bought 1600 ram that was its slowest speed unless you overclocked it. I have also attached images from CPU-Z of the memory tab as well as each stick SPD tab. As you can see at 800 mhz all the memory operates with 9-9-9-24 so it is puzzling me why the memory tab shows 11-11-11-29. Link to comment Share on other sites More sharing options...
Yellowbeard Posted October 10, 2013 Share Posted October 10, 2013 Most likely, since you have an odd memory load, the BIOS is setting more relaxed latencies to compensate for the weird load on the memory controller. You can't always run the same latencies with 3 or 4 modules that you can with 2 modules. Ideally, you need 2 x 8GB or 4 x 4GB. Mixing 3 modules and especially mixing 2 different brands is less than ideal. As long as you are stable at 1600, I'd ignore the latencies. Link to comment Share on other sites More sharing options...
tallguy2682 Posted October 10, 2013 Author Share Posted October 10, 2013 So since I just bought the ram do you think that i would notice any difference in the latency? I can still return it and purchase new ram, the only reason I got this 8gb chip was because it was on sale and I already knew that it would at the very least be compatible with my current setup. I am not sure how much of a difference that small change in latency will make while gaming. Link to comment Share on other sites More sharing options...
Yellowbeard Posted October 10, 2013 Share Posted October 10, 2013 You'll never notice the difference in latencies. Link to comment Share on other sites More sharing options...
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