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  Topic : [Problem]PQ5 - 4Gb OK 8Gb Not New Topic
Gordon
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From: Australia
Posted:9/24/2008 10:59:00 AM # 1
I have recently purchased the following: P5Q Motherboard, 2 sets of Kingston KVR800D2N6K2/4G (8Gb total), ATI Radeon HD3650 Super 512Mb Graphics Card, 300Gb Seagate Sata HDD, 1Tb Seagate HDD, LG DVD Burner etc......

My problem is I can get 4Gb (in either of the KVR800's in either channel) working fine, can access BIOS Setup, loaded and running Vista 64-bit Ultimate with no problems, but when I try to use all 4 DIMM's (ie 8Gb with both channels loaded), the system gives the standard single beep at power on and then absolutely nothing - no video, no further action or response other than the fans and HDD's running - cannot even access the BIOS setup! I have also updated the BIOS version from 703 to 1306 with no change to the problem. Also tried resetting BIOS to defaults, and trying some of the memory settings from similar posts without success.

I have seen similar problems in other forum postings, but nothing conclusive in this situation, - the general feeling I get is that this mobo has a lot of problems when all memory slots loaded!

Does anyone have any ideas on where to go from here?

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Henry
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Posted:9/24/2008 11:22:00 AM # 2
In the bios under the north bridge, do you have memory remap enabled? Also, you may have to up the voltage to the manfacturers max voltage or at least start uping it in steps.
Oh, and did you see the latest bios said it improved performance with some memory.

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Gordon
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Posted:9/24/2008 11:57:00 AM # 3
Cheers Henry. Yes I have Memory Remap enabled, and I also saw the post on BIOS version 1306 supposedly improving the memory compatibilities, but unfortunately for me when I upgraded the BIOS it did not fix the problem :-((,

I believe the KVR800D2N6K2/4G DIMM's are rated at +1.8V (+/- .1V - according to their data sheet), and that is what they are set to at the moment, but I will try increasing the voltage slightly tonight when I get home and see if it makes a difference.

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Mig
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From: Finland
Posted:9/24/2008 8:53:00 PM # 4
Damn, I also have 1 kit (two modules) of the same memory 8-/ Have you tried running the memory in 667 ?

Mig

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Henry
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Posted:9/24/2008 10:49:00 PM # 5

Here is another link on this site that may be related to your problem:

http://vip.asus.com/forum/view.aspx?id=20080924060633828&board_id=1&model=P5E3&page=1&SLanguage=en-us

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Gordon
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From: Australia
Posted:9/25/2008 2:32:00 PM # 6

Hi Mig & Henry,

First of all, I tried last night to increase the voltage settings (without success), but I admit I didn't want to stray too far from the manufacturer's settings for obvious reasons. No Mig, I have not tried the 667MHz settings, in my rather bullish way I expect an 800Mhz DIMM to be run (and supported!) at 800Mhz! Call me quaint.....I mean it not as if 800Mhz is exactly pushing the performance boundaries these days! - and one on my most critical requirements (I do a lot of virtualization testing) is reliabilty.

Henry's link in the previous posting basically adds to my previous observation - ASUS motherboards in general, and in my case the P5Q motherboard in particular seem to have a lot of problems when all memory slots are filled - regardless of the DIMMS used, regardless of their speed and capacities etc. As pointed out in the linked article, if a Memory chip/CPU/whatever is on the ASUS QVL I along with many others assume that means they are supported on those mobo's at their rated specs - and without a lot of "overclocking" and fiddly settings. - End of Rant.

Anyway, I still have not found a definative fix, or even a valid workaround,  for this situation, and if anyone does get a definative resonse from ASUS, please post it for all our benefit. Considering the alternative (get another mobo!) I really would like to "eat humble pie".
Cheers, Gordon

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tcsenter
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Posted:9/25/2008 3:21:00 PM # 7

Quote:
Author: Gordon Posted: 9/25/2008 2:32:00 PM

First of all, I tried last night to increase the voltage settings (without success), but I admit I didn't want to stray too far from the manufacturer's settings for obvious reasons. No Mig, I have not tried the 667MHz settings, in my rather bullish way I expect an 800Mhz DIMM to be run (and supported!) at 800Mhz! Call me quaint.....I mean it not as if 800Mhz is exactly pushing the performance boundaries these days! - and one on my most critical requirements (I do a lot of virtualization testing) is reliabilty.


I wouldn't say quaint, just underinformed.  The limits of all four DIMMs populated with the maximum memory configuration is not an ASUS problem, its a physics problem.  It has always been the rule that when the maximum memory configuration is populated using all four unbuffered DIMMs, the memory frequency may require adjustment downward to compensate for the effects of increased electrical loading. 

The more modules you attach to a memory controller circuit, with more chips or larger capacity chips, the more electrical loading it places on the memory controller and DRAM circuit at any given frequency and timing profile.  This is why server motherboards that offer more than four memory slots (and sometimes only four) require more expensive Registered or Buffered DIMMs.  Registered or Buffered DIMMs use a special register or buffer IC (and sometimes special topologies as in the case of Fully Buffered DIMMs) to mitigate or compensate for the effects of electrical loading, permitting the use of more DIMMs (and chips) at any given frequency and timing profile.

BTW, memory companies advertise their frequencies based on the product configured as it is sold.  e.g.

If you purchase one kit of two modules, any advertised frequency is only valid or assumed for a configuration with TWO modules.  If you purchase two individual kits each consisting of two modules, the assumed configuration is still TWO modules, not four.

The problem with ASUS vs. other companies is that other companies typically make their BIOS enforce the guidelines specified by JEDEC or the manufacturer of the part containing the memory controller (AMD, Intel, NVIDIA, et. al.), to preserve reliable operation at the expense of performance.  e.g.

If you install a questionable memory configuration, other vendors are more likely to have their BIOS intelligently enforce safer operating parameters by automatically downgrading the frequency.  Then, you can manually override what the BIOS has set by default to experiment with higher frequencies.

ASUS often takes the exact opposite approach, allows you to install a questionable configuration, the BIOS dumbly tries to run the memory at the profile indicated by the SPD, courting the risk of no-post or instability.

Two different approaches, not 'quality' differences.  One approach assumes the user may not understand these memory configuration issues and therefore automatically takes measures to ensure reliable POST or boot.  The other approach assumes the user does understand these memory configuration issues and will themselves take the appropriate measures to ensure reliable POST or boot prior to installing the modules.

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Gordon
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Posted:9/25/2008 5:08:00 PM # 8
I must be "underinformed", because whilst I fully understand  - and totally agree with - tcsenter 's technical description, I do have concerns about the assumptions that have been drawn. IMHO, if a memory DIMM (or set etc), is a) listed in the specified motherboard's QVL (and presumably therefore NOT a "questionable configuration", and b) is also listed in the same mobo. manual/QVL as "C*:Supports four modules inserted into both the yellow and black slots as two pairs of dual-channel memory configuration" I believe I have a right to expect that those DIMMS operate as per their specificated speed and capacity. If that is not the case then - pardon my ...... "What the hell is a "supported" configuration???" And until I can see documentation from ASUS along the lines of "these are the exact CAS/Timing reference configuration/Voltage/Speed settings etc. we support this DIMM(s) in each of the possible configurations" then I believe I also have a right to assume that unless otherwise specified, the "default settings" are the supported AND WORKING settings. If I was to go outside those boundaries and started experimenting with the "tweaking" settings then fair enough, it would be on my head (AND VOID ANY WARRANTIES), but I am not doing that - I am just trying to run the board under its stated supported memory modules in their stated default ( and supposedly supported) configurations. At the end of the day, all I want is a reliable, working and supported system.

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tcsenter
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Posted:9/26/2008 12:39:00 AM # 9
I agree that ASUS QVL and memory configuration information leaves a lot to be desired, but its hardly alone.  The ASUS QVL does not necessarily imply frequency.  e.g. A module configuration listed in the section for DDR2-1066 may not actually have been tested @ DDR2-1066.  And it may not be at the BIOS defaults, either.  ASUS may have manually input parameters for some modules, but it doesn't say which ones.

I don't even bother looking at the memory configuration stuff from the motherboard manufacturer, since module manufacturers are always changing the chips used on their modules, it is next to useless, anyway.  I go to the chipset manufacturer and look at the data sheets.

Of the chipset manufacturers, only Intel freely discloses this information, either in the chipset datasheets or the user guides for Intel's own mainboards.  Since AMD's memory controller resides in the CPU, that information is supplied by AMD's BIOS and Kernel Developer's Guide for AMD processors.  NVIDIA has a virtual black-out on any meaningful technical configuration data about its chipsets.  Alternatively, JEDEC defines approved memory configurations as well, but sometimes those are difficult to locate within the dozen documents it publishes for every standard.

But again, you can safely assume that four double-rank (double-sided) memory modules *may* not operate at the default SPD profile unless those four modules are packaged and rated together as a four-module kit.

A two-module kit assumes TWO modules, not four.  Anything beyond the product configured as it is packaged and sold may require manual intervention.  It has always been so.

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Mig
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From: Finland
Posted:9/26/2008 12:34:00 AM # 10
I double checked the memory models and I actually have KVR800D2N5K2/4G and those are listed in QVL and are supported in 4 DIMM configuration. Lucky me.


Gordon: the KVR800D2N6/1G are listed in the QVL. KVR800D2N6/2G are NOT listed, which you seem to have. Maybe you could explain the situation and ask the seller to exchange them to N5 models for little extra, the price difference between those products in Finland is 10%. To me that looks quite resonable solution.


Here are the diffrences from the data sheets:

5 : CL 5 tCK 2.5ns, tRAS 38ns, 1.975W
6 : CL 6 tCK 2.5ns, tRAS 45ns, 2.016W

And no, I don't know how those differences add up. I thought that the slower ones should work better in this case, but it looks like that is not true.

Both of the models seem to appear in the Kingston lists, but that one does not state the 4 module configuration status:

http://www.ec.kingston.com/ecom/configurator_new/modelsinfo.asp?SysID=47940&mfr=ASUS%2FASmobile&model=P5Q+Motherboard&root=us&LinkBack=http%3A%2F%2Fwww.valueram.com&Sys=47940-ASUS%2FASmobile-P5Q+Motherboard&distributor=0&submit1=Search#

Mig

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