First of all, I think there is a bit of misconception. The problems we, the nForce board users, are having with 4x2GB RAM combination "may be partly" because the board itself is having a hard time handling 8GB, but I think the biggest problem is that NONE of these memory are designed or tested to be run in 4x2GB, but only for 2x2GB. All those numbers listed in manufacturers' websites and printed on the modules are valid for a 2x2GB usage, and only that! If any RAM manufacturer is trying to blame nForce boards for problems that's their shame, but I've corresponded with Corsair and Mushkin representatives in the last year and they all confirm (confess) this fact.
Still, nForce boards require higher voltages on the SPP in order to handle the memory load. However, in my experience, that's basically it for the board. It is the RAM that requires serious tweaking in order to find the stable clocks, timings and voltage to be able to run 8GB. Basically, you are doing the testing and QA for your 4x2GB combination yourself, as it was not done by the manufacturer.

Most of you will find that when forced to run in 4x2GB, the RAM will not be stable at the 2x2GB specs. That is absolutely expected and no reason for frustration. In the below, I'm attempting to provide a guideline to tweak your RAM for 4x2GB, assuming that your CPU/FSB settings are 100% stable while running 2x2GB. I strongly suggest using Intel Burn Test @ "Max" for 20 passes to confirm this. I also suggest you read this excellent guide: http://forums.evga.comarchive/tm.asp?m=499530

Here we go;

0) At no time put the RAM clock speed higher than the FSB speed.

1) Before you even start tweaking the RAM settings, make sure that you supply more voltage on the SPP. A good starting point is the first level at or above 1.50V (I don't suggest increasing any further). Don't worry if it's red...

2) In my experience, if the CPU/FSB is overclocked, it required one more notch of voltage in 4x2GB. Yours may not need it but it's OK to give it a bit more voltage to nullify that possibility. So, increase your CPU voltage by one step.

3) Unlink your RAM from the FSB. This ensures that your RAM tweakings will be isolated from CPU/FSB.

4) Enable P1 & P2. That's TWIMTBP

5) Find out what your RAM voltage is spec'ed at and increase your RAM voltage to one notch above that number. E.g., if it's 1.80V, set it to the first notch above 1.80V.

6) To see if you got lucky, put the RAM speed and timings to the manufacturer specs, but pay attention to step 0. For now, use the following timings:

Command Per Clock: 2T
tRRD: 7
tRC: 40
tWR: 12
tWTR: 25
tFAW: 30
tREF: 7.8uS
tRFC: 110

Go to step X-1. If fail, read on.

7) Now you know your RAM needs some tweaking for 4x2GB. At this point, there are two main routes to take. (Actually there are three, but I'm ruling out "Get frustrated and return the new 4GB set").

The first is "keep the RAM clock speed (in MHz) at (or above, if you wanna OC it with FSB by linking and sync'ing) manufacturer specs". For this route, follow steps marked with "A-".
The second is "keep the RAM timings at manufacturer specs"; follow the steps marked with "B-".

A-1) In order to maintain high clock speeds, you will have to loosen (increase) the RAM timings. First, make sure the RAM clock speed is set at manufacturer spec'ed value. Then, increase the tCL, tRCD and tRP by 1, and set tRAS to (tCL + tRCD + tRP). E.g., go from 7-7-7-20 to 8-8-8-24, or from 8-8-8-24 to 9-9-9-27.

A-2) Go to step X-1; if fail, go to step A-1.

B-1) In order to maintain tight RAM timings, you will have to reduce the RAM clock speed. First, make sure you have the RAM timings set at manufacturer spec'ed values, except for those given in step 6 above. Then, lower your RAM clock speed by an increment of 50. If you don't see it applied, lower it by another 50 (this is normal as the board has certain discrete straps, which change with FSB).

B-2) Go to step X-1; if fail, go to step B-1.

X-1) Save and restart. a) You got a looong beep, or a fast BSOD? Don't worry, just go back to where you were. b) Your Windows OS started? Then, continue.

X-2) Run Intel Burn Test @ "Max" for 20 passes. If fail (including freeze or BSOD), go to where you were. If success, continue.

X-3) Run HCI Memtest as follows. Start as many instances as the number of cores on your CPU (say "n"). For the first "n minus 1" instance(s), give a memory size in MB equal to "Total RAM size divided by n", and start them. After that, for the nth intance, start it without modification as "All unused RAM". Wait till all instances reach at least 300% coverage, which you would see at the tiny status bar. If the system freezes or BSOD's before that, go back to where you were. If not, congratulations, you have successfully achieved stability with 8GB RAM.

Save your stable settings in a text file or something, for reference. If you would like to tweak your RAM for better performance, you can go back to the appropriate step. You may need to increase your RAM voltage further for tighter timings and/or faster clock speed; I don't suggest that you go more than two notches above the manufacturer spec'ed value.

You may want to run your RAM linked and sync'ed with your FSB. If your FSB is at the same speed as the current RAM speed, just change the settings to "Linked" and "Sync" and you're good to go. If this requires that you increase the RAM speed, first find the stable settings at that speed using the above guideline and only then apply L&S.

On top of everything, you may want to tighten the timings given in step 6. A fairly plausible set of ranges:

Command Per Clock: 1T-2T
tRRD: 6-7
tRC: 27-40
tWR: 10-12
tWTR: 20-25
tFAW: 24-30
tREF: 7.8uS
tRFC: 90-110

I suggest you change as few settings as possible at a time and with small increments, and I would treat "Command Per Clock" separately. After you make a change, go to step X-1.

If all goes well, you can enjoy 4x2GB while being confident that your system performs as well as it can and as stable as it gets. YMMV, so do not make direct comparisons to others' results...

I hope this helps someone, lol...

PS: Please someone let me know if I skipped anything crucial, thanks...

very good post, this seems to be the source of hurt for most over clockers, bad RAM settings

my 750i sli ftw board runs 4 2gb stick of corsair no problem, however my oc is limited with all 4 sticks.

Great guide Gryphon for those who have trouble getting their overclock stable with 8GB's or just trying to get all 8GB's working at all.

However, I believe you should add that if this is the case, the max speed when all slots are populated is 1088MHz. Anything over that and you basically have to be extremely lucky or you have to loosen settings to the point where you actually get a decrease in system performance.

Most people probably won't have to reach that high but I think it's good just to put it out there. Some people even have trouble getting their 1066MHz stock RAM stable with all 8GB's running at that speed.

Yes Gryphon I was talking about DDR2 for the 750i/780i mobos. Sorry, I forgot to mention that.

As for the wall for DDR2 RAM, it seems the max is 1088MHz but I was saying that even RAM rated at 1066MHz stock was difficult to get all 8GB's of that RAM stable without some tinkering.

I don't have that much experience 790i but I haven't seen anyone running into any walls with 8GB's. Someone correct me if I am wrong.

@ Gryphon 
the same Q 

You should request a Mod sticky this in the 7 Series menu.

theGryphon
I didn't wanna do that myself; it'd be like grading your own test, lol... If you or someone else thinks it's sticky-worthy, you're welcome to make the request though

Done.  I PM'ed rjohnson11 with the request to sticky this thread along with a reason for the request.

Couple of questions. I could not run burntest at max due to the system seeing only 2.50 GB usable out of the 8 GB installed. Actually it show I have 1645 MB available RAM so it will only run the standard test, am I doing something wrong? The standard test passed and also the OCCT CPU test passed but I can't get the GPU:OCCT test to pass. I am running 2 9800GTX cards in sli mode. I have an Ultra 850 X2 power supply. What could I try next. Thanks for any help.

this seems to be the source of hurt for most over clockers, bad RAM settings

That was the prob I had when i started overclocking. I have adata ddr2 1066+ 2x2gb kit, so the default/auto voltages on my 750i weren't enough. Got that figured out now I'm stable.

Hello again gryphon, I decided to use the 8GB in my system as I didn't want to pay the restocking fee, or go through any of that bs, so I threw all 4 stick's in again today after I saw this post.  Read through all of it, great information. 

First time I tried I used the stock Ram frequency, and locked the FSB at it as well to make both the FSB and Ram 1600.  I set the advanced timings as stated and than changed the latencies to 7-7-7-20, with no boot.

Than 8-8-8-24, also, no boot.

Than I tried 9-9-9-27, with a boot, and 20 Max Passes of intel burn test.  Which where the best stable setting's I've seen with my 8gb.

With only 4gb, I could run my CPU at 3.5 ghz, but I knew that the 8gb could possibly prevent me from going that far.  But sure enough, I was able to get my FSB to 1725 (3.45ghz), and ram to 1600 unlinked, which made me very happy.

I might possibly try the opposite setting's you advised for faster timing's rather than high clock speeds, but for right now, I am very pleased with this.


Would you say that if I were able to go for lower latencies with a clock speed of 1333mhz it would be more beneficial?

In any case, great read, very insightful.

Excellent thread! Forgive me if this is a stupid question but, is it better to run (for gaming) more RAM (8GB with all DIMM slots populated) at the slower clock speed or less RAM (4GB with two DIMM slots populated) at the fast clock speed? I am in a situation where I have 2 x 2GB of Corsair Dominator PC28500 DDR2 and 2 x 1GB Corsair Dominator PC28500 DDR2 kits and want to run them all for a total of 6GB of RAM. In my situation would running all the modules together at a lower clock speed be better that just running 4 GB at the normal (faster) clock speed?

Thank you for the advice. That is what I was thinking also.

^ Thanks for the info feniks! You sure are missed here, I'd be very happy if you were around more often!

feniks





it's all been tested million times in old forums. i wish EVGA has never created a new blank forums dropping all the knowledge from old into garbage, shame.

this is one of reasons i'm no longer an active poster around here.

cheers.

Alot was moved and can still be found in the archived version, this new one is more stable it seems. remember all the post flushing that would happen?