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  Topic : [Problem]QPI Frequency and fast memory New Topic
Pierson
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Posted:3/5/2009 5:16:00 AM # 1
Hi -- I'm using DDR3-1866 memory with slight CPU overclocking (BCLK at 150 MHz) and I'm confused about what the QPI frequency should be when running the memory at close to its rated speed. Here's the issue: I've read that the UCLK frequency should be twice the DRAM frequency and that the QPI frequency (as measured in MT/s) should be more than twice that. But this isn't possible if I run my memory at high speed. When I set my memory to DDR3-1805 (using the 12x memory multiplier at BCLK=150MHz), my UCLK frequency will be 3609 MHz. But the _highest_ QPI frequency I can select in the BIOS then is 7218 MT/s (using the 48x multiplier), which is just twice the UCLK frequency -- meaning that it's not possible to select a QPI frequency which is faster than twice the UCLK frequency. Is this a problem? How should I address it? (I'm getting BSOD fairly frequently when I set the memory multiplier to 12x and I wonder if this has to do with why?) All my thanks for any help and guidance! Alan

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Yellowbeard
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Posted:3/5/2009 5:55:00 AM # 2
What specific memory are you using? Also, list all of the BIOS settings you have made for the CPU, RAM, and voltages.

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Pierson
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Posted:3/5/2009 9:21:00 AM # 3
Thanks so much for the response -- it's Kingston PC3-14900/DDR3-1866 SDRAM. Here are my BIOS overclock settings: BCLK Frequency: 150 PCIE Frequency: 100 DRAM Frequency: DDR3-1503 CPU Voltage: 1.23125 CPU PLL Voltage: 1.96 QPI/DRAM Core Voltage: 1.35 DRAM Bus Volage: 1.64 CPU Differential Amplitude: 800 mV I'm using XMP mode, and everything I haven't specified here is set on auto. It all works fine until I try to push the memory up to the DDR3-1805 setting, at which point I get all BSOD.

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Pierson
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Posted:3/5/2009 9:22:00 AM # 4
[p.s. Can anyone tell me how to put line breaks into these posts? I'm putting them in as I type, but they're all removed when I see my post, which makes it awfully hard to read...]

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Fonts
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Posted:3/6/2009 5:48:00 AM # 5
sucks...use an older broswer or get asus to upgrade this forum software...

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1337pete
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Posted:3/7/2009 5:55:00 PM # 6
Leave your QPI frequency on Auto or the lowest level (4.8G/Ts I believe).  This is especially important when OCing your CPU.

Also, I seem to have no problem with line breaks.  I just tap Enter a couple times ...

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Kensek
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Posted:3/7/2009 11:07:00 PM # 7

Quote:
Author: Pierson Posted: 3/5/2009 9:21:00 AM

Thanks so much for the response -- it's Kingston PC3-14900/DDR3-1866 SDRAM. Here are my BIOS overclock settings: BCLK Frequency: 150 PCIE Frequency: 100 DRAM Frequency: DDR3-1503 CPU Voltage: 1.23125 CPU PLL Voltage: 1.96 QPI/DRAM Core Voltage: 1.35 DRAM Bus Volage: 1.64 CPU Differential Amplitude: 800 mV I'm using XMP mode, and everything I haven't specified here is set on auto. It all works fine until I try to push the memory up to the DDR3-1805 setting, at which point I get all BSOD.


Drop your CPU PLL back down to 1.82v.
Raise your QPI/Dram Voltage to 1.40v
Raise your IOH Core to 1.28v
Raise your Dram v to 1.72v

You must keep QPI/DRAM voltage no lower than 0.50v from the Dram Voltage.
Running above 1.65 Dram Volts is fine as long as you run QPI/DRAM higher and as I said, within .50 volts.

I run my old SuperTalent ProjectX Ram at DDR3-2053 with 8-7-6-20 1N Timings at 2.0v but I need to run the QPI/Dram at 1.58v.

Which  brings us to another area   -  Running QPI/Dram above 1.35v is not dangerous.

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Pierson
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Posted:3/8/2009 2:49:00 AM # 8
Many thanks to both Pete and Kensek for the very helpful information. I've been trying out these suggestions and things seem to be working. I've a few follow-up questions: 1. Pete, I've now got the QPI frequency down to minimum (5400 MT/s). I've been told that the QPI frequency has to be more than twice the UCLK frequency -- is this completely untrue? My UCLK frequency (double my DDRE-1503 memory rate) is now at 3000 MHz, which means that I'm breaking this rule, but everything seems to be working fine. 2. Kensek, I want to check that I'm adjusting the right settings. What you call "IOH Core" is marked as "IOH Voltage" in the BIOS, right? And what you call "Dram v" is the "DRAM Bus Voltage" in the BIOS, right? 3. Kensek, when I made these changes initially, the computer wouldn't boot at all. But then I brought the DRAM Bus voltage back down to 1.64 and everything seems fine. Does that make any sense to you? 4. I'd like to get a sense of how speed settings effect how needed voltages. If I raise my memory back up to DDR3-1805 again, I'm guessing I'll have to raise the QPI/DRAM Core Voltage again? Should any other voltages change? And if the QPI Frequency goes up (which it will when I experiment with raising the BCLK further), which voltages should I raise? Thanks so much for all this help! It's much appreciated. Alan

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Kensek
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Posted:3/8/2009 3:04:00 AM # 9

Your right in translating my Parameter Name voltages to what they are labelled as.

But running a Dram Voltage above 1.64 should not make your machine not Post unless there is a Voltage safeguard option within the BIOS enabled doing that.   If so, disable any voltage sensing BIOS options.

Higher Block needs the right balance of CPUv, QPI.Dramv, IOH v and Dram v.

I did this with a 920 on my old Gig Board.

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Pierson
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Posted:3/10/2009 8:59:00 PM # 10
This is great Krensk, thank you -- I've raised the memory to DDR3-1805 and everything seems stable! Can you tell me how you set your voltages to get the overclock you show here? (I see that the CPU Voltage is 1.41 and that the DRAM Bus Voltage is 1.65. What are the QPI/DRAM Core, IOH, and CPU PLL voltages?) Also, can you get it to hold on the 21x CPU multiplier? I thought it only went to 21x in TurboMode, in which case the CPU multipliers go up and down automatically depending on the load. Thanks again! Alan

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