First of all...This is meant to be a basic, quick, overclocking guide for the A8N32 MB. It is based on my own personal experience and will not take you to extremes. It's meant simply for those who want to get started overclocking this MB manually in a safe and logical way.
However, any kind of OC has risk...make sure you understand that, before you start.
Second...you shouldn't even be thinking of doing this unless you have everything 100% stable at the default settings. If you don't, you'll never know if the crashes and glitches you're seeing are due to overclocking or something else entirely (bad driver, corrupt install, bad components, etc.)
Third...I'm deliberately oversimplifying in some cases (HTT is really 2X FSB X LDT = 2000...not 1000, "FSB" is really mislabeled, K8>NB is really the LDT, etc.) just to keep the terms the same way this MB uses them. I'm also using an oversimplified Memory Divider formula. (For the complete accurate and cumbersome formula see the next post.)
FYI...my system is based around an X2-4400, 2 X 1GB of OCZ PC3200 low latency ram and 2 X BFG 7800 OC cards. I am using BIOS 1009.
Settings you should lock (not overclocked):
Cool and quiet: disable
Peg Link: disable (auto by default, but disable it) Peg Link is all about overclocking your video cards--don't even think of doing that at this stage...do it later after you have your CPU/FSB/RAM overclocked if you want. And even then you probably shouldn't do it with PEG link. Riva Tuner and Coolbits is what you should use for GPU overclocking.
SB>NB Frequency: Take it off auto and set it to 200
SB>NB Multiplier: 5X-- This and the previous setting will lock the second HTT that is unique to this MB (to the SLI X16 chipset actually) to 1000...any less and you will loose SLI performance (read the recent review at X-bit labs for more info about this if interested.)
SB>NB Linkwidth: 16/16
K8>NB Linkwidth: 16/16
CPU vCore: for X2 CPUS, set it to 1.2875 to begin. This MB will automatically add 0.0625v to that, giving you 1.35 which is the AMD recommended (1.3 - 1.4) setting for X2 CPUs.
All overvoltage settings=off
USB legacy: disable...if enabled it WILL cause problems with Memtest (test 5 & 6) and perhaps, with RAM performance. More info about this at the Memtest support forums.
Memory command rate= 1T...the default is Auto but you should set it to 1T if you can. If you have 4 sticks of ram then you just have to live with 2T. There is performance degradation going to 2T from 1T.
FSB = 250. This is a 25% OC of the FSB...this MB can do much, much more...this is a mild OC.
CPU multiplier: For an X2-4400 set it to 10...this overclocks the CPU to 2.5 GHz from the stock 2.2 GHz...A modest 13.5% overclcok: why this setting? Because it's more than what the ASUS AI OC will do (max 10%) and is still very safe at default voltages...just to wet your appetites With a different CPU that has a different default clock setting, set whichever multiplier gives you something in the 10 to 15% range above the rated speed. For example if the default is 2.0 (200 X 10), 250 X 9 gives you 2.25 for a 12.5% OC.
NOTE: there are no guarantees here...some CPUs are dogs and someone unfortunately ended up with them... a 15% OC is not guaranteed for ALL CPUs. Personally, I've never had a CPU that couldn't do that, but your mileage may vary.
K8>NB Multiplier: 4X. The default FSB and HTT in an nf4 AMD64 system are 200 and 1000 respectively. HTT is simply the FSB multiplied by the K8>NB multiplier (LDT)...so default for the K8>NB is 5X. This motherboard has been reported to be able to do well with an HTT as high as 1200 (300 X 4-Hardocp review)...that's the good news. The bad news is that there is absolutely zero measurable performance increase to be gained from overclocking the HTT...play it safe and always keep the FSB X K8>NB at 1000 or lower.
Memory limit: set it to 166...166/200 X 250 (FSB setting) = 208...this is a tiny 4% ram overclock. All PC3200 ram should be able to handle this with the tightest timings which is why I'm being so conservative here. Ram overclocking is a different art and when you want to max your ram settings you are going to have to start making 1000 little tweaks that are very specific to your ram. You'll be better off going to the ram support forums for your type of memory and looking for clues there on what your sticks should be able to do and the looser settings to get you there.
All other memory settings...leave at Auto. This should keep your ram at the tightest timings it tells the MB it can do. In general, when overclocking ram with an AMD64, tighter timings are better unless the looser timings get you more than 20 MHz more. This is simply my own "rule of thumb" based on my own benchmarking and observations made by many others who have tested this...take it with a grain of salt (you may get a performance increase in whatever you use to benchmark with just 12 more MHz ) but it works for me.
Don't pay any attention whatsoever to whatever the BIOS post screen says your memory is clocked at...it will not report the FSB X divider/200 results...use something like Everest or CPUz in windows to check the ram frequency.
Testing and benchmarking:
There are many good utilities out there for testing your memory (Memtest) overclocks and the overall Windows 2D overclock (Prime95, etc.) And you should use those when you're ready to max things...personally I skip those and go straight to 3Dmark 2006. Why? Because I have never had an OC that would do 3Dmark well and fail elsewhere...but the opposite is definitely true…and ultimately, with an SLI system, 3D game stability is what I'm interested in...It's not 100% OC Geek certified methodology...but it works for me. I do use Memtest and Prime95--just not for "quick & dirty" overclocking when I have a good feel for whether I'm pushing things or playing it relatively safe.
Quick and dirty troubleshooting hints:
If adjusting the BIOS results in no boot and a black screen (worst possible case) try to access the BIOS set-up by pressing and holding the INSERT key (not the delete key) This usually will get you to the BIOS screen but sometimes you'll just have to go and reset the CMOS manually…first time you do, you will curse ASUS for putting the jumper right under the retaining clip for the bottom video card.
If your CPU can't do 15% at default voltage settings there are 2 things you should do:
1. Leave everything else the same but start reducing the FSB from 250 by 5 at a time until you reach stability. This will tell you what it CAN do at stock voltage.
2. Take it back to 250 and start increasing the voltage 1 notch at a time until you reach stability with the FSB @ 250...watch your temperatures whenever you add voltage. Now it's your call whether you want to take the lower OC from #1, the higher voltage from #2 or something in between.
If you suspect your memory can't do the tiny 4% OC: 1. take the divider down to 133...this will take it out of the equation...if you still have the same problems, it wasn't the memory. If the problem is fixed by taking it down to 133, then bring it back up to 166 and increase the ram voltage a notch...you can keep trying this all the way up to 2.9 afely. Or, go seek help at the memory manufacturer's forums. Just as an example...my memory will do 230 @ 2.7 volts but I have to loosen timings from 2-3-2-5 to 2.5-3-3-7 to do so.
Where to go from here:
Anandtech's quick and dirty overclocking guide: If you want to get serious about finding what your components can really do, this guide will help you find the maximum FSB this MB can handle (probably 330+), the maximum frequency your CPU can handle and the maximum speed your RAM can do...and then integrate those 3 factors to give you the best possible overall overclock for your system.
Taken from Cisco's post at NforcersHQ
link to Gogars' OC calculator