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Best i7 memory speed without OC'ing?

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November 4, 2009 12:29:41 AM

I am planning an i7 build (920 or 975), my first ever build, on an x58 motherboard (either EVGA or Asus) with 12 GB of DDR3. I am using this build for some heavy Photoshop and HD video rendering work. I don't want to overclock anything, and I recognize that memory speed is not nearly as important as overall memory size. Typically the motherboard's maximum memory speeds are said to be 1333 or 1600, and the best brands on the QVL like OCZ and Corsair are only represented in the 1333 and 1600 sections. Yet the i7 apparently doesn't "support" anything faster than 1066.

What does that mean, the i7 doesn't support faster memory speeds than 1066?

I'm just confused on the seeming contradiction between the mobo specs and the processor specs as they relate to supported RAM speed. If I were to go with 1333 MHz, and if I set the timings in BIOS to reflect that, would this count as "overclocking" my memory, since I am exceeding the i7's specs? Or not, since I am still within the higher specs of the mobo?

I just want to get the 1333 MHz RAM that the QVL recommendsin order to get a quality brand, but if it means that I'm going to be tweaking and troubleshooting and starting fires at home due to memory overclocking, then I'm a little intimidated. Does anybody get the i7 processor with 1333 or 1600 MHz RAM without overclocking, or is that an oxymoron?

Can somebody please clear this up for me? I am clearly confused.

Thanks,
Brian

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a b } Memory
November 4, 2009 2:52:15 AM

You mention "the i7 doesn't support faster memory speeds than 1066" but give no source for this odd bit of information. For clearly the motherboards DO support such faster memory. I'm no expert on the i7, but it may be that its RAM controller bandwidth is 1066, but I'd be surprised it wasn't 800.

The best way to make sure your RAM doesn't require any tweaking is to buy good quality, reasonable speed, low latency and low-voltage RAM. This means 1333 with a Latency of 7 and a voltage of 1.5V.

I would recommend this RAM from G.Skill - two sets of 3 - 2GB modules for 12GBs
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

It's unlikely to need any type of modification of the BIOS settings but that depends on the motherboard - you may need to simply tell it you have 1333 RAM. In addition, anytime you add 6 modules instead of just 3, you may have to increase the DRAM voltage a little - no way getting around this.

You may well get better performance by not overclocking, but simply making sure the BIOS recognizes the characteristics of your RAM such as its latency. This is not a difficult process - and you do it once and forget it. Telling your computer that you have a fast Hard drive and installing its driver, or a good video card and its driver is not only reasonable, but required. Telling your BIOS you have good RAM is the same thing - worth the trouble but NOT usually required, just common sense.
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November 4, 2009 10:10:23 AM

Thanks for the reply. Check out the Intel Processor FAQ at http://www.intel.com/support/processors/sb/CS-029913.ht..., with this particular quote:

"What is the maximum frequency for DDR3 memory when used with Intel® Core™ i7-900 processor series?

These processors support DDR3 memory with a maximum frequency of 1066 MHz. If faster DDR3 memory is used (such as 1333 MHz or 1600 MHz), it will be down-clocked to operate at 1066 MHz."

So... it looks like faster RAM will be downclocked. So maybe if I just 1333 MHz with Latency of 7 and 1.5v, I'll be fine with the downclocking and won't need to modify the speed in BIOS as long as I make sure the BIOS reflects the latency of 7.

The bigger issue is that the motherboard QVL for the RAM is pretty tilted toward higher latency 1333/1600... not many low latency choices. I can always go into the EVGA forums to ask though.

Thanks,
Brian
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a b } Memory
November 4, 2009 10:23:58 AM

brianz, that article by Intel just doesn't make any sense to me. They're basically saying that their slower i7 processors will work with faster RAM than the faster one? I don't think that's right and I know that RAM over 1066 is never downclocked. I'm going to share this article with a friend here who posts in the Gigabyte forum and who really knows both RAM and Intel specs, see if he can explain it - I'll post answer here or link to that thread.

I think the answer will revolve around the memory multiplier used by the BIOS to match native CPU/memory controller freq to RAM freq.

But for now, pretend you didn't read this by Intel! Any number of motherboards support 1333 RAM or faster for i7 / 1366. But 1333MHz is the best - lol, you can find articles which say this!

That Intel article also says that anything above 1.5V RAM will damage the CPU - that does not match Intel's actual standards which say 1.5V to 1.65V.

You cannot go by the QVLs. Those are created by the engineers at the factory grabbing whatever RAM they have had sent free to them and testing it in the system. Often it's RAM you've never heard of, but might be sold all over Taipei! And it's usually older models that date to the first testing of the motherboard - and perhaps old then. It's not uncommon to see 3 - 1GB kits listed as 2 - 1GB options and other errors of kit/size - where they pulled out 2 modules from a 3 module kit or listed 2 module kits for a 3-module requirement.

So the QVL lists are generally pretty useless.
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November 4, 2009 10:37:23 AM

Thanks very much, I'll be interested in whatever else you can find out. Maybe some joker in marketing just put that FAQ together, who knows. I've seen reference to that 1066 limit elsewhere though, so there's something going on with that.

I'll look for low latency 1333 MHz DDR3 and will run it past by the EVGA support forums and the forums here before pulling the trigger.

Thanks,
Brian
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a b } Memory
November 4, 2009 11:26:23 AM

Sounds good! Speaking of marketing, don't fall for those fancy heat-spreaders and precious-metal names - look at the specs on the RAM! Also, RAM made overly tall with gadgets can interfere with after-market CPU coolers if you decide to get one. And with a high-end CPU, even w/o OCing, a cooler is a good idea. The rendering process will tax your CPU as much as gaming and some cooling is good for the life of the CPU.

The other thread is created - can chk it yourself or get informed of answers if you reply to it.
http://www.tomshardware.com/forum/265449-30-article-int...

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