Asus A8N SLI Deluxe 1:1 Ratio Overclocking Guide

MADMAX23

Senior member
Apr 22, 2005
527
0
0
For those who are trying to run their systems (based on the Asus A8N SLI Deluxe mobo) with 1:1 ratio at high HTT/mem clock speeds, say 250 Mhz - 255 Mhz, I think this might help you a little bit:

1) Flash/update your BIOS to 1006 revision: I do recommend this Bios and not the last one, 1007, because after testing it the results were frustrating. Summing up, my system would not even load Windows with the same config I have been using for weeks with great stability under Bios 1006.This was/is my everyday settings:
- HTT 252 Mhz
- CPU: vcore:1,425
Multiplier: 9´5x 252 x 9´5 = 2400 Mhz
- RAM Memory: DDR 400 must be selected in Bios in order to achieve 1:1 ratio
Timings: 2.5-3-3-7 1T
vdimm: 2.75v
- Hyper Transport Multiplier: 4x
- PCI Express Clock: 100 Mhz
- PCI Clock synchronization mode: 33´33Mhz

2) Enter the Bios and FIRST go to ADVANCED > CPU CONFIGURATION > DRAM CONFIGURATION: Here the values you should not change or vary are these:
- Hyper Transport Frequency: 4x
- Max MemClock : DDR400
- 1T/2T Memory Timing: 1T
The memory timings is a very particular matter: You should already know the capabilities of your Ram memory, if not, please, ask or get informed somehow.
I am telling you this because I do not recommend you to let the timings on AUTO mode since the motherboard sets very relaxed timings usually and that means lower performance, that?s why you should know the overclocking potential of your Ram modules as well as their aproppriate timings.
We are trying to get a 250 Mhz mem clock, that?s a PC4000 (500 Mhz) Ram memory module, if you own one of those simply check out the manufacturer?s specified timings and set them in the Bios.
Entering the RAM timings in the Bios: For the rookies this may be tricky that?s why I am going to explain you the following: Imagine you have a DDR memory module with these timings printed on your ram 2´5-3-3-7 The first number (2´5) always represents CAS Latency (?Tcl? in Bios) as it's usually the most important. The second number (3) represents RAS-to-CAS Delay (?Trcd in Bios?), the third one (3) represents Row Precharge Time (?Trp? in Bios) and the last one (7) represents the Min RAS Active Time (?Tras? in Bios) (which is always the final, and largest number). So, be careful when setting the timings!!

3) Afterwards, go to ADVANCED > JUMPERFREE CONFIGURATION:
Set the Overclock profile to Manual
CPU Frequency: rise it to 240-255 Mhz (as desired, the one your ram and chipset supports)
PCI Express Clock: 100 Mhz (always)
DDR Voltage: depends on your RAM modules (Do not go over 2.85v if you are not sure of your Ram specs/capabilities)
CPU Multiplier: This is the clue!!! After tough testings, it seems when working with 1:1 mode the only stable Cpu multipliers for this board are the decimal ones, I mean, non integer numbers as multipliers (ex: 7´5, 8´5, 9´5)
This ?rule? applies to HTT frequencies beyond 240 Mhz, for the low ones integer multipliers (7, 8, 9, 10) also work.
Recommended CPU Multipliers: 7´5, 8´5, 9´5 (all tested)
CPU Voltage: This depends on the actual Cpu speed, anyway;
References:
2´2 Ghz: 1´4125v (tested)
2´4 Ghz: 1´425v (tested)
2´6 Ghz: 1´5v (not tested)

PCI Clock Synchronization mode: 33´33 Mhz (always)

Last but not least, Go to BOOT > BOOT SETTINGS CONFIGURATION: Here in OS Select DRAM > 64 Mb, select OS2 if you have more than 64 Mb of RAM memory installed on your computer.

EXIT AND SAVE CHANGES

START TESTING: I would suggest you to begin searching for the highest HTT your Ram/Chipset supports in 1:1 mode. For this purpose, start with a HTT speed of 240 Mhz with a 7´5 Cpu multiplier with stock cpu voltage and go rising it if your system is stable!
Good luck








 

GuitarDaddy

Lifer
Nov 9, 2004
11,465
1
0
The reason you can only get above 250mhz using the .5 multis is because with the half multis you aren't really running the stated HTT. A64's don't support half multis so the motherboard bios plays a little trick, it actually uses the next highest whole multi and adjusts your HTT down. Your 252 x 9.5 = 2394 is really 239.4 x 10 = 2394
 

Regulator07

Senior member
Feb 15, 2005
517
0
71
Originally posted by: MADMAX23
Last but not least, Go to BOOT > BOOT SETTINGS CONFIGURATION: Here in OS Select DRAM > 64 Mb, select OS2 if you have more than 64 Mb of RAM memory installed on your computer.

what does this do, i know i have mine set to non-OS2 but could never quite figure out what it is for. also you say always set pci express clock to 100, i have heard that settng it to 101 makes sure it is locks, is there any evidence that doing that is true or is setting it to 100 fine ( i assume using ntune is how you check that?). thanks
 

steamnputer

Member
Mar 3, 2005
139
0
0
Originally posted by: Regulator07
Originally posted by: MADMAX23
Last but not least, Go to BOOT > BOOT SETTINGS CONFIGURATION: Here in OS Select DRAM > 64 Mb, select OS2 if you have more than 64 Mb of RAM memory installed on your computer.

what does this do, i know i have mine set to non-OS2 but could never quite figure out what it is for. also you say always set pci express clock to 100, i have heard that settng it to 101 makes sure it is locks, is there any evidence that doing that is true or is setting it to 100 fine ( i assume using ntune is how you check that?). thanks

I always thought that was for OS2 the operating sytem(anyone remeber that)as a legacy, at any rat this MOBO needs to have at least 256MB anyway, so why would you even need this?

 

MADMAX23

Senior member
Apr 22, 2005
527
0
0
Check the HTT speed with CPU-Z 1.27, ClockGen for NF4 or Sisoft Sandra and you will see that the real speed of the Bus is in fact 250Mhz, not 239 as you say.
Bios 1007 is not any better than 1006 in terms of overclocking!
I you set the Pci Express to 100Mhz it will be locked, check it with Clockgen > Get values > then rise tthe HTT frequency, you will see that PCI Express Clock stays at 100 and so does the PCI Clock Synchronization mode at 33.33 Mhz.
Hope this helps!
 

MADMAX23

Senior member
Apr 22, 2005
527
0
0
To Guitardaddy!
If you run tests with the DDR333 divider you will discover the following:
Half multipliers are crap, only integer multis seem to work properly right?
I will post another express guide to overclocking with DDR333 divider, my CPU has reached 2,715 Ghz by now with a stable HTT speed of 300 Mhz and a Men speed of 251 Mhz..and I can tell you that is real mem speed!
Just check it out..and tell me what you got!
 

MADMAX23

Senior member
Apr 22, 2005
527
0
0
Guitardaddy!
I ran some tests yesterday to discover you were damn right!! This mobo tricks us when using half multis and high HTT frequencies, you were right, after tough testings and comparisons, I discovered that using half multis in 1:1 ratio with an HTT higher than 240 Mhz, the mobo applies a divider without warning you and all programs except CPU-Z 1.28.3 will tell you you are running your RAM at the spped you expected.
Thanks Guitardaddy, now I know new interesting aspects of this board.
I will post the several test resulta I got when comparing the different configs!
A little example, the performance achieved with 240 Mhz HTT x10 (CPU Multi) is way better than the one I used before.I will report the results later.Now, my efforts are focused on reaching the maximum HTT speed I can with the 10 and 9 multis.
We'll be in contact!
Note: I am running my Corsair memory at 2-3-3-7 at 240 Mhz (PC3800)