Memtest errors with 8GB on P5Q

Phil99

Phil99

Phil99

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29 Oct 2004
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Due to some fairly intensive Matlab work I've been doing I've upgraded my system from 2x2GB GeIL DDR2 PC6400 to 4 sticks, the new sticks being the same model as the old (GB24GB6400C5DC). I was hoping to avoid issues like this by buying memory on the QVL, but it never seems to be that simple...

Problem is, even when I pump up to 2.1v through the memory and 1.5v through the NB I still get Memtest86+ (v2.11) errors on test 5 or 7. I've tested both sets seperately and no issues, tried changing the only options on the Northbridge page of the BIOS (memory hole/remapping) but no difference.

Specs are:

P5Q (latest BIOS)
Q6600 - stock settings
4x2GB GeIL PC6400
485w Enermax PSU

Everything in terms of voltages/clocks are at default/auto except for the memory/NB voltages which I've tried boosting.

Any ideas?
 
Northbridge seems pretty toasty, it's got a tuniq tower above it but I don't think that really does a lot for airflow in the area. RAM doesn't feel all that hot.

Will the northbridge temperature be the system temp in BIOS? CPU usually runs at about 40 degrees give or take a couple of degrees per core.
 
Do you get crashes etc in windows when using MatLab or is this just testing to make sure the memory is working correctly?

I have a P5Q deluxe, and i did find a strange bug with memtest and the ASUS bios. My overclock was unstable but since it was prime stable etc on the CPU side, i assumed it was the memory, and sure enough Memtest gave loads of errors. Turning off USB legacy support stopped these errors completely, and aside from a BIOS bug, i cannot think of an explanation. If your getting crashes in windows, then it is posibly a genuine problem, but i though i would throw this out there in case you experience a similar problem. Took me ages on google to find a solution!
 
Ah, I may well try that later on a fresh install. I really can't afford to corrupt any files/programs so I've jut been memtesting before even re-attaching my boot disk.

Will report back on how I get on with those suggestions, I'm currently re-testing the 4GB that arrived today on their own to make 100% sure I don't have any faulty sticks. Will probably try with 6GB as well.

Thanks
 
Well it seems ok in Memtest86+ now I've set the tRFC to 60 and memory speed to 709MHz down from 800Mhz. Voltages are now 2.0v memory and 1.36v chipset.

Tried creating an 8GB vector in Matlab on Ubuntu and appending a copy to itself (so lots of swapping about in memory) and it didn't crash so initial testing is promising.

I'm going to install Vista64 later today and try the USB legacy setting. Still, strange issue considering this board is apparently supported up to 16GB and the memory has been tested by ASUS as being able to run as 4x2GB. Not desperately happy with that but if it's stable now I can't complain too much I guess!
 
Phil99 said:
Well it seems ok in Memtest86+ now I've set the tRFC to 60 and memory speed to 709MHz down from 800Mhz. Voltages are now 2.0v memory and 1.36v chipset.

Tried creating an 8GB vector in Matlab on Ubuntu and appending a copy to itself (so lots of swapping about in memory) and it didn't crash so initial testing is promising.

I'm going to install Vista64 later today and try the USB legacy setting. Still, strange issue considering this board is apparently supported up to 16GB and the memory has been tested by ASUS as being able to run as 4x2GB. Not desperately happy with that but if it's stable now I can't complain too much I guess!
Click to expand...

The tRFC value will be the answer. :) I know with 4Gb you need to have a value around 45+. So I can see the logic here that you have to set a higher value for stability when using 8Gb.
 
Firegod said:
The tRFC value will be the answer. :) I know with 4Gb you need to have a value around 45+. So I can see the logic here that you have to set a higher value for stability when using 8Gb.
Click to expand...

I tried with the same tRFC value and DDR800 and got an error on test 7 within 2min, is there a signifcant hit when increasing tRFC? I notice the values go quite a lot higher so there's definitely head room to increase it. I imagine it's a case of finding the correct balance between frequency and tRFC?

I suppose it's worth a go though, would be nice to get DDR800 working properly as long as a much higher tRFC won't have too much of an impact on speed :)
 
Phil99 said:
I tried with the same tRFC value and DDR800 and got an error on test 7 within 2min, is there a signifcant hit when increasing tRFC? I notice the values go quite a lot higher so there's definitely head room to increase it. I imagine it's a case of finding the correct balance between frequency and tRFC?

I suppose it's worth a go though, would be nice to get DDR800 working properly as long as a much higher tRFC won't have too much of an impact on speed :)
Click to expand...

Yeah that's it at the end of the day, it's about finding the right balance. So perhaps set it high, and work down. Shouldn't take too long. Maybes do it in jumps of 5 and just run MemTest Test #7 until it errors. :)

http://forums.tweaktown.com/f69/memory-timings-explained-w-suggested-timings-memset-vs-bios-27283/

tRFC Timing: (Refresh To Act Delay) Row Refresh Cycle Timing. This determines the amount of cycles to refresh a row on a memory bank. If this is set too short it can cause corruption of data and if it is too high, it will cause a loss in performance, but increased stability.
 
Just noticed this as well in that link....

Refresh to ACT Delay (tRFC)___________ 38-42 (2X1GB) 52-62+ (2x2GB)

So that may give you a ball park figure as to where to start. :)
 
Tried starting at 100+, 2.0v memory, 1.36v chipset, DDR800, otherwise standard settings and I get a memtest error within 2min, there's only one higher setting of over 130 which seems a bit high so I'm wondering if the problem lies with a different setting.

I'll give that link you posted a proper read later as it looks like it could be useful, I'm yet to also try the suggestion of disabling USB legacy support but I need to find a PS/2 keyboard adapter as I need to be able to select the test # in memtest.

In the mean time, is there anything else I should be considering in terms of BIOS settings? There's certainly a lot more memory options than my old systems :o
 
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