New i7 Rig - DDR3 1600 Posting as 1066 Mhz - Help?

[Drew Carey]

Hi guys,
You can find my new PC thread in the General Hardware Section, I just bought and built the following rig:

CPU: Intel Core i7 920 2.66Ghz 8MB Cache BOX
M/B: Gigabyte GA-EX58-UD4P
Video: Leadtek GTX260 216 Extreme+ GeForce 896MB
RAM: OCZ PLATINUM DDR3 6GB 1600MHZ - OCZ3P1600LV6GK
HDD: Samsung 1TB 32MB 7200RPM SATA II HD103UJ Spinpoint F1
PSU: PC Power ULTRA-QUIET PSU SILENCER® 750Watt QUAD
Case: Thermaltake V9 VJ40001W2Z Window
Optical drive: LG DVD-RW X18 - IDE 133
Monitor: Apple 20' LCD "Cinema Display"

Everything seems to work great, except my RAM posts as 1066Mhz/1.5V only (instead of 1600Mhz/1.65V). Am I missing something? Is the X58 somehow limited in a way I wasn't aware of?
I double checked with CPU-Z which reports the same thing.
I double-checked the modules, and they are definitely PC-12800, 1.65V parts.

I'm running with BIOS F7.
I can change the FSB-RAM ratio manually in my BIOS, but I don't feel like this is standard procedure.

Would greatly appreciate some help...
Thanks in advance...

 

[Denithor]

Originally posted by: Drew Carey
I can change the FSB-RAM ratio manually in my BIOS, but I don't feel like this is standard procedure.

That's exactly what you gotta do if you want your shiny new fast RAM to run at its rated speed.

Memory and CPU speed work from different multipliers of the BCLK.

At stock speeds your system looks like this:
BCLK = 133
CPU = 20x133 = 2.66GHz
RAM = 8x133 = 1066MHz

The only way you can actually use that memory at its rated speed is to overclock the BCLK (and you can decide whether or not you want to OC the CPU or not).

BCLK = 200
CPU = 12 to 20 x 200 = 2.4GHz to 4.0GHz
RAM = 8 x 200 = 1600MHz

DDR3-1600 is really only meant for overclockers - there's absolutely no need for anything above DDR3-1066 if you plan to run your i7 at stock speeds.

You should also know there's very little real-world difference between memory running at DDR3-1066 and DDR3-1600 speeds, especially on an i7 with its massive triple-channel memory bandwidth.

 

[iCyborg]

He could also set the RAM multi to 12x, this would get him exactly 1600MHz with stock BCLK. He'll need to set the DRAM voltage and latencies himself, unless he has profiles.

 

[Drew Carey]

Thanks for the replies guy's!
What's the difference between these two methods? In terms of memory performance and theoretical bandwidth.
Changing just the RAM Multiplier and voltage sounds like the safer route, as I would not be touching the BCLK, CPU clock or QPI - and since I'm not interested in overclocking or risking any of the components, I'm liking the idea more.

If anyone knows a guide that explains this stuff, I'll be greatful...

Thanks for the help!

 

[alcoholbob]

Change the voltage to ~1.65 (the highest "safe" rating) and manually set it to 1600mhz and 8-8-8-20 or thereabouts.

The difference between 1066mhz ram and 1600mhz ram is typically no more than a 1.5-3% performance boost, which is to say, a 100mhz cpu overclock would run all over it.

 

[jandlecack]

The best way is to just change the memory multi, as previously suggested. That way you don't need to overclock anything and can run your RAM at the rated speeds - but don't forget to set its other values accordingly e.g. voltage and timings.

 

[Drew Carey]

Thanks for the help guys.

I've upped the multiplier and voltage, without touching the uncore, QPI/VTT, and things seem fine (I should stress test some more, but so far so good).

I haven't touched the timings in the BIOS (as they seem to be 7-7-7-24 in there), but CPU-Z recognizes them as 10-11-11-24. Did I just increase latency by upping the frequency and not touching the uncore? Essentially not gaining anything?

I've got to learn this stuff more thoroughly...

 

[KILLER_K]

Wow 10-11-11-24, something is way off somewhere. You should download the newest cpu-z which is 1.52 beta and it now sports a video tab.

 

[Denithor]

Unless I'm mistaken the i7 920 only offers memory multipliers of 6 and 8 (meaning at stock BCLK you can choose between DDR3-800 and DDR3-1066). The extreme chip (965) offers the higher multipliers of 10 and 12, unlocking DDR3-1333 and DDR3-1600.

So on a stock 920 DDR3-1066 is your fastest option.