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Another bewildered P8P67 user


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To save time, please assume I'm pretty much clueless with this stuff.


I've just built a new machine - Asus P8P67 Deluxe mobo with an i7 2600k CPU and FOUR x 4GB DDR3 ( CMZ8GX3M2A1866C9 ) sticks. I've got a Corsair H50 cooler on the CPU, which probably isn't too relevant yet, but might be with the auto-tuning stuff in a minute.


I've run the mobo in pretty much vanilla mode - certainly haven't done any OC'ing yet, until I actually confirm everything's sane with the machine. I did do the BIOS upgrade from ASUS (v1606 I think).


Anyhoo, most of my work is done in Debian GNU/Linux, but I noticed when I switched over to Win7-64 and cranked up Speccy that the RAM was showing as running at 667MHz.


I followed a few other threads in this forum and that led me to fiddle with the BIOS settings - specifically changing AI from 'auto' to 'X.M.P.'. On reboot, the RAM is running at 933MHz.


Another thread suggested that setting AI to 'Manual' and setting the speed to 1600MHz and the timings to 9-10-9-27 would work better. I did this, and rebooted, and now the memory is running at 824MHz.


I'm totally bewildered. I thought the memory should run at somewhere around 1600 or 1866 MHz, without having to do any OC'ing, or (naively) without having to dig into the BIOS too much.


Happy to take any hints at this point. I'm still digging around the forums and my BIOS, but feeling somewhat daunted.

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Thanks Wired - the multiplier stuff is something I really need to get a better handle on. So 933MHz is what I should be expecting to see as stock - good to know. I'll revert that change in BIOS for now and enjoy the easy power. :)


Two more dumb questions then, while I'm on a roll.


Could you explain where the ~667 came from? That suggest somewhere around 1330MHz, but that doesn't sound like a magic number I've seen for any of the components.


When you say the rated speed of ONE kit - I'm not being penalised here for having two lots of 2x4GB kits in this thing am I?

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The 667 x 2 multiplier is the default the bios selects if XMP is not selected.


1333 is the "industry standard" as defined for motherboards currently.


Anything higher is technically an Over Clock and has to be set manually or through XMP.



As for question 2, Mixing two kits is not guaranteed to work at the manufacturer's rated speed for just one kit due to variences in production and supply.

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DDR means DOUBLE DATA RATE. so you are 667x2 =1333 mhz speed that your processors memory controller defaults to


When you say the rated speed of ONE kit - I'm not being penalized here for having two lots of 2x4GB kits in this thing am I?

No , it's just not recomended to mix sets like that. You should always buy the capacity you want as one tested kit. Even two kits with the exact same part number,version number and so on can be made of entirely different chips. This is not suggested or supported by Corsair officially. Most users who do this often have problems with the two kits playing well with each other and more than not have to lower the frequency of the memory to get them run together. So if you start having problems down the road that would be the first place to check. I am in no way saying that you will, it's just that most do , but there are a few lucky ones that have had success getting this to work without a penalty to speed. The other factor in this is having all slots on your motherboard populated. This puts a greater stress on the memory controller and can also result in having to lower RAM frequency's. So if your machine is stable at 1866 with 2 kits you are most definatly one of the lucky ones! :)

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Guys - thank you for explaining this. I'm sure these questions come up regularly (and I have been off reading some more OC guides in the interim), so I very much appreciate your patience.


I'm seeing stability (or a good approximation of same so far) with my two x 2x4GB kits at 933MHz. One of the reasons I upgraded recently (from an aging quad Core2) was because I couldn't source identical sticks to the 2x2GB I had on it, and I really needed more than 4GB - and it's precisely the reason I splashed out on 2 of these 2x4GB DDR3 kits up front, as I didn't want the same pain in a year or two from now, being unable to find something to match.


Actually the (pretty large) vendor I bought these from here in the UK don't have 4 x 4GB kits as an option - I'm guessing they must be quite the speciality item. I'm used to working with servers, where 16GB is nothing special, but I guess it's a bit excessive for a desktop machine.

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