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  #1  
Old 09-21-2007, 06:23 PM
Andreas7506 Andreas7506 is offline
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Default Asus P5K memtest errors

Hi

I just got a new system with a Asus P5K mobo and 2x Corsair TWIN2X 6400 DDR2 1024Mb memory modules (total 4Gb).

My problem is that i get a lot of errors in Memtest86 if i run with default BIOS settings. I also tried changing timing and voltage to get the system stable, but the only thing that works seems to be to set the DRAM frequency to 667MHz...

Are there any good tips for getting the modules to run at 800 MHz or do i just have to live with 667MHz?

Will increasing voltages make the system more stable at 800MHz?

Or should i just remove 2Gb of RAM?

Regards
//Andreas
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  #2  
Old 09-22-2007, 01:58 PM
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Set your Vdimm to 2.1V. Retest. If you continue to get errors, set your speed to 667Mhz. Retest.
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  #3  
Old 09-24-2007, 01:28 AM
Andreas7506 Andreas7506 is offline
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Hi,

Thanks for your reply.

If i set the DRAM clock to 667 MHz the system is stable, MemTest86 does not report any errors.

I guess i'll just have to live with my memory clocked to 667MHz instead of 800MHz..

Regards
//Andreas
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  #4  
Old 09-24-2007, 01:59 AM
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Are you running 4 X 1024MB or 2 X 2048MB. Are you running Windows 32bit or 64bit?
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  #5  
Old 09-25-2007, 11:30 AM
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Hi

I am using 4x1024 Mb and i run Windows Vista... I don't know what the OS has to do with MemTest though...

Regards
//Andreas
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  #6  
Old 09-25-2007, 12:32 PM
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Regarding my question on 32bit vs 64bit Windows. If you are running Windows XP 32Bit or Windows Vista 32bit, then you are not gaining much benefit from the 4GB as the 32bit operating system is not very robust with memory addressing.

Since you are running 4 sticks of DRAM, you will need to drop your DRAM speed. The issue is not the DRAM. The issue is that mainboards are at this time not optimized for 4GB and doubly so when the 4GB is populated in 4 slots. The chipset memory controllers have to work harder with more denser modules and double the DRAM means that there has to be a longer que to await the data delivery. A longer que means that it will take longer for the data to be accessed and this means that the columns and rows need to be open longer which means that you need to slow down the DRAM somewhat to be able to achieve stability.

So, if you are running Windows 32bit or Vista 32bit, then I advise you remove 2 of the sticks. If you are running Windows XP 64bit or Vista 64bit then I advise you drop your speed to 667Mhz.
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  #7  
Old 09-25-2007, 12:39 PM
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And I would try and set the NB/MCH Voltage to + .05 Volts and set the memory voltage to 2.0 Volts and see if its stable with www.memtest.org.
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Old 09-28-2007, 10:44 AM
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I have three machines of the exact same setup, and with the exact same problem. I'd noticed that clocking the memory lower actually helped, but I wasn't content to leave it at that. Right now I'm testing the memori at 1.95v instead of letting it run according to SPD (1.9v).

There's a definite improvement, before bumping the voltage the machine didn't even survive 15 minutes in memtest86, but now it's been running for over an hour. I'm not doing my victory dance yet, but it's looking good so far.

Question is, should I exchange the memory modules for something that will work as is, or should I live with having to over-volt modules that aren't being overclocked? Thing is, these machines aren't for me so it would be good to have it all as simple as possible without the need for me in the future when they reset their BIOS for some reason or other...

Thanks, and I'm looking forward to hearing if Andreas got it working as well =)
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  #9  
Old 09-28-2007, 12:21 PM
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With 4 modules DDR667 would be suggested and I would set the memory voltage to 2.0 to 2.1 Volts and as I stated previously set the MCH/NB Voltage + .05 Volts as well.
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  #10  
Old 09-28-2007, 02:22 PM
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Quote:
Originally Posted by RAM GUY View Post
With 4 modules DDR667 would be suggested and I would set the memory voltage to 2.0 to 2.1 Volts and as I stated previously set the MCH/NB Voltage + .05 Volts as well.
What might the MCH/NB voltage thing be called in my BIOS you think? The option I find called "north bridge voltage" can't be set in small increments, it's 1.25v, 1.40v, 1.55v, and 1.70v only...

I might add to this that the 4 DDR800 modules I'm running are doing just fine at 2.0v, I've been testing for several hours in memtest86. It failed before the voltage bump, and I've tried setting the voltage to auto to see if that would make it fail again, which it did. Back to 2.0v, everything is working fine. This is the original memtest86 v3.3 mind you, not the + one. memtest86+ fails no matter what I do voltage and DDR667/800-wise, I think that's probably more of a problem in the software than the hardware.
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  #11  
Old 09-28-2007, 03:46 PM
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Yes set the "north bridge voltage" up + >05 Volts or the next setting +.
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  #12  
Old 09-29-2007, 01:56 PM
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Quote:
Originally Posted by RAM GUY View Post
With 4 modules DDR667 would be suggested and I would set the memory voltage to 2.0 to 2.1 Volts and as I stated previously set the MCH/NB Voltage + .05 Volts as well.
Allright, the system didn't survive the overnight testing for DDR2-800 with the voltage at 2.1v and NB at 1.4v. Switched to 677 at 2.1v for memory and standard for NB, which has been grinding away in memtest86+ for five hours now.

This may be a fix for the systems to be stable, but not a full one to my mind. Couldn't this motherboard and/or these memory modules be considered defective? They aren't living up to the claims sported in the system specs at all. I have to run them at lower speeds to get it to work, and even with some voltage tweaking at that. Feels to me like buying a brand new ferrari only to have to send it to the shop before being able to use it, and finding out it's a porsche under the hood... In any case, would it make sense to see if other modules run better so I might exchange the current ones? I mean, is it possible that this combination of motherboard and RAM doesn't work, but other memory types like XXXXXXXXX might work fine with no extra tweaking? Also, I'm not sure if this is the sort of thing the next BIOS update release will fix, but it seems to be taking a while between releases.

Thanks again for all your help, much appreciated!

Last edited by Drezn; 09-29-2007 at 01:59 PM. Reason: Clarification on last question
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Old 09-29-2007, 02:09 PM
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The Problem is not the DRAM Drezen. The issue is that the motherboard chipsets are not optimized to run the DRAM at full speed when all four banks are populated. Some can get away with tweaking their settings and overclocking the CPU/Chipset to create a smoother relationship to the Chipset <--> DRAM transfers.

Edit: If you installed 4 sticks of 667Mhz DRAM, then you would very likely have to drop to 533Mhz to find any real longterm stability.

Think of it this way. If you have a small phone book, then when you go into the index to find the page where you will find the phone number you are doing so at a certain speed due to the pages of the Index. Then you have to drive through the pages to get to the number. Now if your index is twice as large and the pages twice as many, then it takes longer to access the data. Now DRAM has a Strobe and the length of the strobe is how long the rows and columns can be left open before they must be refreshed. There is not enough time for the dram to be refreshed and then accessed with 4GB at the full access speed of the DRAM. The chipsets are optimized for 2GB, not 4GB. This is changing and of course there are some who can overclock the FSB to gain some extra bandwidth and thus access the capabilities of the DRAM since the chipset is now clocked up. Usually when you clock up the FSB and concurrently the Memory Controller Hub (MCH) you need to raise the voltage of the MCH a bit.

So, if you raise the FSB of the CPU, the FSB voltage, Possibly the CPU voltage and the MCH voltage, you may be able to reach the 800Mhz as now the chipset is running faster and can keep up with the additional access duration of the 4 banks of populated DRAM. Setting the Vdimm to 2.0 - 2.1V is pretty much necessary and also the FSB Voltage and the MCH voltage need a bit of a bump as well. As I said, some might get stability this way, but most will not and since stability is so important, it is far better to drop to 667MHz.

Now if you were saturating your bus at 667, then an overclock of the CPU <--> FSB <--> MCH would be a good idea but as it is, I personally think it is not necessary. Unless you want the extra speed of the overclock which will also create a more stable relationship with the CPU FSB <--> MCH.

I Hope this explains the issue for you.

Last edited by DerekT; 09-29-2007 at 03:41 PM.
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Old 09-29-2007, 03:46 PM
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Thanks for the full explanation buddy, nice of you to go through the trouble to write all that down

I do have a basic grasp of the deeper functions of the RAM game, and I'm still amazed at the poor stability of this system. I'm am not, and im not planning to overclock. Everything is set to auto in BIOS (system defaults to DDR2-800), and it's still not stable when set to DDR2-667 manually.

Having to go in to adjust the voltage to this and that part of the system just to get it running after manually setting a lower speed on the memory is just bad. Whether it's the chipset, motherboard, or memory modules, it's definately not OK. If I were trying to force it to run at 800 I could see the problem, but this is what it tries to do on it's own.

So what do I do? Exchange the parts that aren't working together? I'm pretty sure it can work as my mate bought the exact same setup except the graphics card, but from a different store. He's running everything at the auto detected speeds and voltages, and it's fine. I'm thinking he may have gotten another batch of the same type of memory? Is that a possibility you think? Otherwise this is beyond odd...
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  #15  
Old 09-29-2007, 04:10 PM
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If you are looking to populate all four banks with DRAM and hope to run that dram at it's maximum spec, then you are playing a try and hope it works game. There are some 680i (ASUS Striker, etc) chipset boards that are more forgiving at the chipset level. Other than that, I don't think you will have much luck.

I understand your feeling that since the board is said to support 800Mhz DRAM, then it should support it at all levels and not just one level, that being 2 DRAM banks populated. Sadly, that is not the case in the industry and that is why it is massively important to research heavily. Keep in mind, that the 680i is more forgiving, but it is not a certainty that you can populate all four banks and get 800Mhz on your 800Mhz DRAM.

I am a system's integrator and am just giving you the benefit of my knowledge in building systems. Yes, there is always a possibility that one can install 800Mhz DRAM and set to Auto and gain the 800Mhz speeds when populating all four DRAM banks in an Intel chipset motherboard. The P5K is a bit more forgiving in this event. However, I have never seen it happen.

In the final analysis, you can go to your systems integrator and ask them to give you what you want. Good luck!

Last edited by DerekT; 09-29-2007 at 04:14 PM.
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