Memory expansion causes bluescreens

[mattswe]

Hi!
My Asus P5B-E has worked fine with 2x1 TWIN Corsair XMS2 Extreme 800, 5-5-5-12. Now I want to insert 2 more to get 4GB, (and I know Ill only get about 3GB). The new ones are identical but with 5-5-5-18. The problem is when inserted I get bluescreens all the time. Im usning Vista (32bit) and XP(32bit) on the same comp and both gives bluescreens.

What does BIOS look like?
I use BIOS v. 10.2. The memory remap feature is disabled (32bit os). The latencies are manually set to 5-5-5-18 and memory voltage to 1,9V. This is what those memories are speced for. Overall stock specs settnings, no overclocking.

What have I tried so far?
- If removing the old memories and inserting the new ones, everything works smooth, so no bad RAM.
- Doesnt matter which memory sockets I use, as long as I only fit 2GB, everything works well. So the memory channels seems to be ok.
- Tried increasing the memory voltage to 2,0V. Didnt do nothing.

It looks like it is the amount of memory (>2GB) that causes the bluescreens.
So, do you have any ideas?
Matt

 

[MMclachlan]

Hi, For info those sticks are EPP rated at 2.1v Vdimm at 4-4-4-12.
When you run 4 sticks they usually require a touch more voltage than spec, I run 4x1Gb dominators at 1066 with 2.13v (vs 2.1).
Anyway, I would put your Vdimm up to 2.1v which is the spec then start increasing your Northbridge voltage as this is most likely the cause of the crashes. Running 4 strips requires more power at the northbridge. Default is 1.25v so go up in increments until it is stable. (I run 1.5v through my N/B which is running an overclocked Q9550 at 3.4Ghz, 425Mhz FSB - although if you are not overclocking you won't need anywhere near this much, probably <1.4v)

 

[MMclachlan]

Oh, once you ahve them stable you can set the RAM timings to 4-4-4-12 as mentioned

 

[mattswe]

Thanks for the tip. I hope Ill get some time tomorrow to try it, Ill be back with a report.

 

[mattswe]

This is great! I increased the memory voltage to 2,1V and yet no bluescreens. Didnt even have to change the Northbridge voltage.

One thing is really goofy though. While BIOS says I have 3008MB Windows Vista says 4GB. But when measuring with a more reliable program, I do have 3008MB inside Vista too. Its like Vista wants to cheat me to think I actually have 4GB for my disposal.

Thanks for your help. Just one more question. Will the fact that I use 4x1GB memory sticks and not 2x2GB limit my chances to overclock the memory? Cause I have to turn the voltage up just to make them stable?

Matt

 

[MMclachlan]

You have 32bit Vista so it can't actually use the full 4gb, google this or search the forums for a more detailed explanation!
Traditionally you will get better (faster) results using 2 sticks than 4, as it is less work for the n/b to address 2 sticks as opposed to 4. I've never been much into serious overclocking of RAM, I tend to try and get the timings as tight as possible - as close to the rated speed as possible. Although I do have 2Gb of the exact same RAM as you in my front room PC and that dynamically clocks the CPU up and also up to 940Mhz on the RAM under load and they have always been fine at that speed (with 5-5-5-18).
You will get similar performance though by setting your timings to 4-4-4-12 and leaving it at around 800Mhz. For example going from 800Mhz 4-4-4-12 to 1066Mhz 5-5-5-15 is actually only a 6% increase in performance due to the timings, as you have to loosen them as the speed increases. It depends on what your N/b will do. My brother's P35 board will run two Dominator sticks at 1066 5-5-5-15 but refuses to run 4 sticks at that speed whatever the n/b voltage - we even went with looser timings and tried up to 1.65v!! However it is quite happy to run all four at 850Mhz with 4-4-4-12 timings and only 1.33v on the northbridge. You'll just have to see what works best, and if you run into any stability issues up the n/b volts one step at a time.

 

[geofelt]

Some motherboards are sensitive to different ram technology. The tech used to build a stick may differ, even if the specs are the same. That is why it is better to insure the same technology by installing ram in a 4gb kit.

I would run memtest86+ for a few passes to make certain that the ram is solid.
Then I would run prime95 with checking for rounding errors which will test the ram in a different way.
If your ram configuration is not sound, you need to fix it first.

Yes, it is harder to overclock 4 sticks vs. 2.