Complete BIOS Tuning Guide - "Memory Timing Setting"

Memory Timing Setting

P1 - [Auto, Enabled] We can tell you this setting optimizes internal MCH latencies when setting an FSB of 475MHz or greater, but the exact functionality is unknown at this time. Enable this option when overclocking above 475FSB to gain back some memory read performance and improve memory access latencies. Below 475FSB, this option has no effect (Auto maps to Enabled by default). You may need to increase NB Core Voltage (SPP Voltage) when this setting is Enabled.

P2 - [Auto, Enabled] This setting should also be Enabled if possible when clocking above 475FSB. Typically, you will have problems with "P2" if your system in unstable with "P1" Enabled. Enabling both "P1" and "P2" will result in the greatest memory read performance improvement.

tCL (CAS Latency) - [Auto, 5 ~ 18] As a rule of thumb, use 6 below DDR3-1600, 7 from DDR3-1600 to about DDR3-1830, 8 from DDR3-1830 to about DDR-2000 and 9 for anything above DDR3-2000. Not all memory is the same so you will need to experiment to see what works best. Besides the actual memory speed, the selection of this value has one of the greatest impacts on the memory voltage required for stable operation (lower values leads to higher voltages).

tRCD (RAS to CAS Delay) - [Auto, 1 ~ 15] You cannot go wrong setting this to the same value as tCL. Sometimes you can set this to tCL -1 without the need for any additional voltage; just do not expect a big change in memory read bandwidth.

tRP (Row Precharge) - [Auto, 1 ~ 15] Like tRCD, set this to the same value as tCL or use tCL -1. Typically, if memory will handle a tRCD of tCL -1 then you may be able to get away with tRCD -1 one for tRP. Again, try different values and go with the lowest number you can get away with without the need for excessive memory voltage.

tRAS (Active to Precharge Delay) - [Auto, 1 ~ 63] Never set a tRAS lower than tRCD + tCL + 2. Contrary to popular belief, tRAS is not as much an actual timing as it is a minimum cycle time. Lower values are almost guaranteed not to improve memory performance but stability can go south in a hurry if you are too aggressive with this timing.

Command Per Clock - [Auto, 1 clock, 2 clock] Generally speaking, 1T command timing should be good up to about DDR3-1860 with 2GB of memory. Save yourself the hassle and use 2T whenever overclocking with 4GB or 8GB of DDR3.

tRRD (RAS to RAS Delay) - [Auto, 1 ~ 15] We recommend you set this value to 1 and leave it there.

tRC (Bank Cycle Time) - [Auto, 1 ~ 63] This is arguably one of the most important timings when it comes to memory performance with NVIDIA chipsets. The rule when it comes to tRC is you should set it no lower than tCL + tRAS + 2. Even small reductions in this timing can bring about large decreases in memory access latencies.

tWR (Write Recovery Time) - [Auto, 5, 6, 7, 8, 10, 12] Tighten this to 10 if you can. Some memory will go as low as 8 if you feed it enough voltage.

tWTR (Write to Read Delay) - [Auto, 1 ~ 31] This setting is best left on Auto.

tFAW (Four Active Window Delay) - [Auto, 1 ~ 63] Try setting this to whatever you use for tRC. Those that are overclocking 8GB of DDR3 may need to loosen this significantly above DDR3-1600 or so.

tRD (Read Delay) - [Auto, 1 ~ 15] This timings was added at our bequest starting with BIOS 0504. Unfortunately, the chipset does not respond to this option in the manner in which an Intel chipset would. For now, ignore this timing as if it did not exist (leave on Auto).

tRTP (Read to Precharge Delay) - [Auto, 1 ~ 15] This setting is best left on Auto.

tRFC (Row Refresh Cycle Time) - [Auto (0), Manual to 255] Set a tRFC of at least 72 when clocking 8GB of DDR3 above DDR3-1600. Otherwise, the board handles adjusting this option automatically quite well. A small amount of memory read performance can sometimes be gained with moderately lower values. Go too far though and you will be greeted with a BSOD during OS load.

tREF (Refresh Period) - [Auto, 3.9, 7.8] Leave this on Auto as the correct value is read from your modules SPD (typically 7.8μS).

Complete BIOS Tuning Guide - "Extreme Tweaker" (Cont'd) Complete BIOS Tuning Guide - "Over Voltage"


View All Comments

  • Rodriguez - Friday, June 20, 2008 - link

    Can anyone here indicate how to reach FSB 500 (2000) with Striker II Extreme & QX9770 C1, most I can get is 1900FSB.

    I've seen Kris reach this speed in this article & was eager to get to this speed as soon as I received my new CPU, but it has been more difficult than I thought, I was sure that if with my previous Q6600 G0 y could easily get 1900/1950FSB, now with QX9770 would be peanuts. The main reason I bought this CPU was to run 2000FSB linked & synced with Ballistix 2000 SLI.

    Please give all detailed BIOS setup options for this CPU if possible

    Nobody in Asus forum using this setup has been able to reach 2000FSB, but I have seen a few reviews (like Anandtech's) & posts showing it's possible

    By the way, memory has been tested unlinked at 2000Mhz 9-8-8-24, 1.9v P1/P2 Enabled & works great


    QX9770 rev. C1 3.2Ghz (watercooled)
    Asus Striker II Extreme BIOS 801, ver 1.02G (watercooled)
    PC Power & Cooling Turbo Cool 1200W
    4 x 1GB Crucial Ballistix PC16000 SLI EPP2 , 2000Mhz 1800 8-7-7-24- 1T - 1.9v
    SLI Leadtek PX8800 Ultra Leviathan (factory watercooled)
    SLI Leadtek PX8800 Ultra
    Asus Physx card (removed)
    Dlink DWA556 PCIx Xtreme N Wireless card
    2x WD Raptor 150GB Raid 0 300GB
    1x Seagate 400GB Sata
    X-Fi Platinum Fatal1ty Champion
    24' Benq FP241VW Gamer
    Innovatek XXD Rev 2 + G-Flow water cooling
    CoolerMaster Cosmos 1000 case
    Saitek X52 Flight system
    TrackIR 4 + Trackclip Pro
    Windows Vista Home Premium 32bit
  • parkerdw - Tuesday, June 3, 2008 - link

    I used the same motherboard and cpu, but I liquid cooled it using the gigantic Kandalf Liquid Cooled case. My memory is different as well since I use 4 GB of Patriot Viper memory (2 x 2GB). Other than the memory settings in the BIOS, I set everything to match this guide. My system runs at 4.0Ghz and the cpu runs at no more than 88 degrees fahrenheit even while playing something like Crysis with everything set to Very High. Crysis runs between 35 and 60 fps on Very High on my system using a single 9800 GX2 at 1280 x 720. It's a HTPC connected to my older 56 inch DLP set via DVI, so I can't go any higher than that, but I fully expect to run great at 1080p when I get my new large screen set later this year. I don't have my bios settings in front of me, but setting everything to Auto for the memory works PERECTLY at 4.0 ghz. Pretty cool. I think it's running at 8,8,18 or so and 1.9v.

    Also, Asus just released a patch to the bios that fixes the data corruption issue mentioned in this artcle. Released on 5/29/08 I think.
  • hardist - Monday, April 21, 2008 - link

    The water block seems to have leaking issues , I am wondering why it was not covered in this review since it is a major feature of this board ...... Reply
  • Heatlesssun - Sunday, April 20, 2008 - link

    This is a sweet motherbaord! Now I've not overclocked the FSB, just bumped up the multiplier of my QX9650 from the default of 9.5 to 10, and I'm not running RAID. We shall see but I feel good. To get this up and running with Vista x64 in a day so smoothly was pretty good I thought. Reply
  • electricx - Tuesday, April 15, 2008 - link

    So this board is going for the aforementioned amount on newegg... The EVGA and the XFX 790i boards are going for $350... The ROG name carries that much of a premium? I mean, come on?! I'm sure ASUS will fix this data corruption issue and you typically do pay more for the privilege(?) of being a beta tester for high end hardware but $1000 over competing products seems a bit much... The EVGA board is looking to be a clear winner here to me. Time will tell I suppose. Reply
  • FightingEagle - Friday, April 18, 2008 - link

    After the second EVGA 790i and full of bugs I just sent it back. I was interested in the ASUS X48 and the 790i, but the 790i over $400 is hard to grasp. EVGA has good looking heat sink but not very good at cooling. I may wait for all the bugs to leave but as now im sitting on $320 dollars worth of DDR3 and a E8400. Reply
  • electricx - Tuesday, April 15, 2008 - link

    Edit: That should have been $100 not $1000 Reply
  • UK1Man - Sunday, April 13, 2008 - link

    Help please!!
    I'm currently in the process of building a computer but can only afford to buy a couple of parts a month, I have already purchased some DDR2 (1066) memory for an FXF 780 motherboard (not yet purchased) but am now considering the Asus striker II extreme.
    Will my DDR 2 memory work with this?
  • seamusmc - Monday, April 14, 2008 - link

    This board/chipset, 790i, only supports DDR3. Reply
  • ianken - Saturday, April 12, 2008 - link

    Can it go into S3 suspend and come back out and have the NICs still work? The Striker 2 Formula cannot.

    Can the SATA controller handle hot swap? The Stiker 2 Formula and the previous 680i boards could not. The 680i bios even had an esata setting that did NOTHING.

    The latest crop of Asus boards, particularly the NV chipset rigs, have been pretty buggy and basic functionality has been borked.

    But hey, who cares of the basics don't work right? it's got a water block for X-TREME OVERCLOXORS! YO! VTEC!

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