X48 Rampage Formula Preview.

[Alien Grey]

By looks of it hus bandwidth is cripped slightly from adding extra Advance on DRAM delay skews to pull off PL6 without too much extra Vnb and keep the thing stable. That's my take on it anyhow.

A-Grey,

Not bad mate, good to see you took those clown shoes off and got the thing working a bit better

By the way the CPU/NB clock skew delay increment is limited by the resolution achieved through MCHBAR register adjustment which as you imagine is what Intel designed into the MCH. I've never seen a bios use anything but 100ps steps on X48/P45, all vendors alike. This pretty much confirms it is achieved through MCHBAR registers since not all vendors use same clock generator.

Now I don't have the faintest idea where you will find the value, but I have a rough idea. It'll be somewhere between either 000-100h or B00-FFFh. First range looks like it holds initialization values, and the second range contains registers which are used for clock driving/receiving/compensation and GTL+ circuit adjustment, such as MCH slew rate, MCH vref adjustment, GTL buffer strength, Host slew Rate input, etc. So if anything it should be in here.

Basically Asus are stuck with the same adjustment steps that everybody else is. Intel obviously didn't go any higher with resolution because cost to manufacture would go through the roof, and I don't think they'd be able to just say well we gave the overclockers higher resolution clock skew adjustment, so all your chips are now worth $50 more to purchase. They'd have stock that'd never sell

If you google a little bit you will find enough pages that can show you that Gigabyte boards have these 50ps clock skew increments, including the X48 Chipset boards. This is probably one of the reasons why it's a lot easier to run at high FSB's on these Gigabyte boards.

I think that ASUS boards don't have them because nobody ever asked for them.

My settings for 8 X 465MHz and DDR 1239MHz with tRD 6 aren't bullet proof. I didn't completely remove the instability I just moved it a little further with raising the CPU Voltage just enough to do 25 passes of LinX. I know that if I do more passes at some point it will fail.

I hope that ASUS is going to see the problem know too and that they change the increments to 50ps.

There's one thing I know. The ASUS Engineer didn't tell me that it isn't possible to have 50ps clock skew increments. There's still a chance that they add it in a new BIOS release and I hope that they add tREF too.