Mr nister969,
I can say that I expected that. Since your mem is SLI ready it is no wonder that you have a 1GHz SPD setting. What you see in cpu-z is your normal SPD settings along with the EPP setting.
Since this is an nVidia based board that supports EPP memory you should be able to use your memory's EPP setting of 1000. What you have to do is find the SLI-Ready memory option in BIOS. This is in the System Clock Setting sub menu of the MB Intelligent Tweaker screen. There you will have to play a little with the cpu oc/expert option and hopefully you will have no big trouble finding the right settings for your mem to operate at 1000.
Everything else related to mem should be set to auto but the mem voltage. The mem voltage should be set as high as the mem manufacturer allows without invalidating your warranty.
By using the EPP setting of your memory it is likely that this will lower your timings, BUT, the overall performance of your mem should increase because of the speed difference (800 vs 1000). Best thing is to measure your mem's performance before enabling the SLI-Ready option and after you do that. My favorite utilities for that are Sandra and Everest.
I've also had my fair share of long beeps, reboots and system boot ups with the backup BIOS and all of them were mem related. This is of course because I like to tweak my memory and I've avoided ocing my cpu so far.
What all of these taught me is that it is a very good thing to have a different ver of the BIOS as a backup (preferably one ver of the official BIOS prior to the latest) and also to have some profiles saved for each of the 2 BIOSs (main and backup). This is good policy when ocing or tweaking, as whenever the backup BIOS kicks in, the profiles of the main BIOS cannot be accessed but the profiles of the backup are there. As soon as you get back on your main BIOS the profiles you saved under it are still there like nothing happened. This will save you some time as you will always have the relative profiles at hand for the BIOS you have booted under.
It may also be a good idea to load fail safe defaults before you try anything with your mem. This of course will ruin your oc but this would be just a temporary setback. From my experience its much harder to tweak/oc your ram than your cpu. The kapt'n 's advise is also something to consider, especially if you intent to go further than your EPP setting.
For testing your RAM I recommend running multiple instances of memtest for windows. you will probably need 4 of them for your 4 GB setup.
You can download memtest for windows from here :
http://hcidesign.com/memtest/download.html
A word of caution. Accept nothing less than 0 errors. Mem integrity is crucial. Acceptance of errors will result in your OS failing if not now maybe tomorrow or next week ....if you 're lucky. I always have a Norton Ghost image close in case that mem tweaking kills my OS. I encourage you to do the same.
Kapt'n
As soon as I get my new cpu I will be more than happy to tell you what I'm getting in terms of memory performance. However, the performance gains from 800 to 1066 is not that big as you may think.