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Higher Clock Memories runs unstable

Posted on 2008-10-28
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Last Modified: 2013-11-10
Hi,

Got this strange problem with my system...

Gigabyte GA-EP35-DS3P
Intel E8400  (Not overclocked)
Corsair XMS2 DDR2 800MHz 4x1GB
Antec TPQ850W
Galaxy EN8800GT 512MB
500GB HDD
Windows XP Pro SP3
....

Anyway, i was trying to upgrade my memory from PC6400 800 to PC8500 1066MHz (same capacity e.g. 4x1GB) . But unfortunately encountered stability issues using 1066MHz, erratic Hanging on either BIOS , Windows Startup and even doing normal stuff on windows (e.g netsurfing, downloading, etc...) Tried running memtest on PC8500 memory (one at a time, then all connected) but it all passed (on at least 2 passes).
And when i placed back my PC6400 everything runs normally again (i.e. no instability). I've searched through Corsair knowledgebase but could not find same scenario.

Has anyone experienced this problem/s? Was it solved?  Any ideas where to check next after memtest?
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Question by:jsuanque
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by:_
ID: 22828610
A lot of mobos have 'issues' running 4 sticks of ram.
While it looks like this mobo doesn't mind 4 sticks of 800 ram, the 1066 is stressing the memory bus,

You can usually fix this by manually loosening the ram timings one step and raising the voltage .05 to .1 higher.
example: if the specs on the 1066 ram is 5-5-5-12 @ 2.2 volts, go into the bios and set it to 6-6-6-12 or 15 @ 2.25 / 2.3 volts.


With unbuffered memory, every memory chip (16 per module with double-sided modules) represents one load on the address and data bus drivers ... with 4 modules that's 64 loads !!   The square wave looks more like a very sick sine wave at that point ... with very poorly defined transitions.   For a bit more detail, play Item #10 in this presentation:
http://www.corsairmemory.com/memory_basics/index.html


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by:PCBONEZ
PCBONEZ earned 35 total points
ID: 22832242
I agree with coral.
A little about what he's saying:
Data is 1's and 0's in the form of pulses in a square wave.
Faster timing means higher frequency of pulses (pulses are closer together in time).
Memory is actually a bunch of tiny capacitors with a 1 being a charged cap and a 0 being a discharged cap. The transition between a 1 and a 0 isn't instant, there is a small amount of time involved.
There is a point where changing between a 1 and a 0 is occurring so fast that the system can't keep the wave form clean (distorted square wave) because the signaling power (power source to charge the tiny caps) is overwhelmed and the caps don't charge to a full 1. (so to speak) That causes misreads. (Some 1's are mistaken for 0's).
Lowering the timing will give the caps more time to reach a full 1 voltage before the next timing pulse.
Raising the voltage will help the tiny caps charge a bit faster reducing the transition time between a 0 and a 1. (Raising voltage too much will cause other problems including overheating those banks of tiny caps.)  
- Each will help clean-up the shape of the square wave in a different way.

To answer the next obvious question:
Memtest is less load on the power source because it only accesses the memory in one place at a time where as in operation the memory is accessed in many places at the same time.

.
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by:knoxzoo
ID: 22845128
Specs on that board are:
   1. 4 x 1.8V DDR2 DIMM sockets supporting up to 8 GB of system memory
   2. Dual channel memory architecture
   3. Support for DDR2 1200 (O.C.)/1066/800/667 MHz memory modules

So, it should be good with that RAM, based on your description.

However, if what the folks above noted doesn't work (it should), it may be a case of BIOS burn-in.  There are a lot of claims that BIOS burn-in doesn't happen, but I've seen it far too many times to discount it.  The BIOS gets stuck, for whatever reason, on a particular memory and/or CPU configuration, and will not change.  Sometimes a BIOS update will correct this.  Sometimes a complete CMOS clearing will.  But, most often, when I've seen it, the only option was to leave things the way they were.  

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by:jsuanque
ID: 22847390
Got interested on Coral's suggestion. Tried it and didn't experience problem after windows started up but still got the erratic hanging during BIOS start-up. Haven't totally figured it out but anyway, will try clearing CMOS tonight (Knoxzoo's suggestion) and retry Coral's suggestion again.
By the way, i'd really appreciate the explanation you guys gave. Seems that there so much i don't understand yet when it comes to memory.
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by:
_ earned 60 total points
ID: 22847519
This is going to be one of those problems. huh.   : /

A couple of things:

- when you clear the cmos, unplug the psu from the wall, and take out the battery, then move the jumper. also press the power button a couple of times. this will make sure there is no charge to the cmos to keep the settings from clearing (rare, but happens)

- see if there is a new bios update and if it says anything about fixing ram bugs.

- try loosening the timing 2 numbers. you might need a touvh more voltage also, but do NOT go more than .2 (point 2) higher than the stock specs. If they are 2.2v, then 2.4v is as far as I would take them.

- you might have a border-line ram stick installed, or that particular mobo might not like those particular ram modules.
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by:knoxzoo
knoxzoo earned 30 total points
ID: 22851861
I just realized - none of us even thought to ask if you'd checked to make sure the memory hole for OS/2 was turned off in the CMOS.  I know it's not a very likely happening, but it could have gotten turned on by accident, power spike, etc.  

Just for S&G, swap the ram around.  Move 1 to 4, 4 to 1, leave 2 and 3.  Try it out.  If still goofy, leave 1 and 4 and swap 2 and 3.  

And, make sure CPU and RAM timing are set to standard or automatic in CMOS, except when testing coral's ideas.  If you had the system set to turbo mode (or whatever they're calling it on that board) with the old ram, but didn't turn that off with the new stuff, funky things just might occur.
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Author Closing Comment

by:jsuanque
ID: 31511032
Goodie...Goodie...Goodie...Problem solved. Thanks guys.
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by:_
ID: 22883137
Thank you much.   : )
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