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jmke 7th November 2004 03:07

INFO: Explanations of DFI NF3-250GB Bios settings/Ramtimings
Excellent read! check here for updates

All these options are as of the 10/15(4.0vdimm)beta bios.

I will start with the ram options

Most of which were tested with my BH-6, but some testing with my Hynix ct-d5(will test more indepth with it later)

Last updated 11/06/04 9:35 pm....

RAM Timings/options

  • White= Timings/Options that we are used to seeing in other bioses...

    (PS alot of these timings i will not mark in this way such as CAS/tRCD/tRP/tRAS, because most of us are used to their results..)

  • Yellow= Options usually not seen in bioses, but some modded bioses, or a64 tweaker will allow you to excess them

  • Red= Timings VERY rarely/never seen in Bioses, and not seen in A64 tweaker

  • Underlined Words= Options avalible in A64 Tweaker By CodeRed...

  • *Star= slight influence Bandwith

  • **Star= Very influential Bandwith

  • star*= Slight influence stablity

  • Star**= Very influential Stabilty

  • *star*= Sligth influence in both stabilty and bandwith

  • **Star**= Very infuential in both stability and Bandwith

[FONT=Arial]DRAM Timings[/FONT]

**Dram Frequency Set(Mhz)**= 100(Mhz)(1/02), 120(Mhz)(3/05), 133(Mhz)(2/03), 140(Mhz)(7/10), 150(Mhz)(3/04), 166(Mhz)(5/06), 180(Mhz)(9/10), 200(Mhz)(1/01).

This option sets the Dram ratio. with a64, the ratios are not always writen in stone, for example 166(5/06) isnt always 5/6 ratio. you can refer to this chart for the exact ratios(they may not all be right, and thanks to Oskar_WU for his help with the chart)

**Command Per Clock(CPC)**= Auto, Enable(1T), Disable(2T), this is also called Command rate.

It is best, in most cases to use Disable(2T) with 2x1gig, 2x512, or 1x1gig Ram modules for the best stablility. 1T yeilds better performance, and 2T usually yeilds the best stabilty/overclock


*Cas Latency Control(tCL)**= 1, 1.5, 2, 2.5 3, 3.5, 4, 4.5. I would suggest only using, 2, 2.5, and 3..

This is the first timing that most ram companies rate there ram with. For example, you might see ram rated at 3-4-4-8@275mhz. this is the 3, in than situation.

2 yeilds the best performance, but, unless you have either Winbond BH-5, or BH-6, it is unlikely you will beable to reach you maximum overclock at CAS2. CAS3 is usually yeilds the best stablility/overclock.


**RAS# to CAS# delay(tRCD)**= 0, 1, 2, 3, 4, 5, 6, 7. I would suggest only using 2-5

This is the second timing that most ram companies rate there ram with. For example, you might see ram rated at 3-4-4-8@275mhz. this is the 4, in than situation.

2 yeilds the best performance, and 4-5(5 is usually overkill) yeilds the best overclock. Most rams will not be able to use 2, and reach there max OC.

*Min RAS# active timing(tRAS)*= 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, 15.

This is the forth timing that most ram companies rate there ram with. For example, you might see ram rated at 3-4-4-8@275mhz. this is the 8, in than situation.

This is a very debated timing. Some may argue that 00, 05, or 10 is the faster/most stable. but i really think there isnt a right anwser for this one, it all depends on your ram. But, if you need a good starting point, usually most/all rams can accieve there max OC on 10 tRAS, even if one of the other setting is faster.

**Row Precharge timing(tRP)**=
0,1, 2, 3, 4, 5, 6, 7. I would suggest using only 2-5.

This is the third timing that most ram companies rate there ram with. For example, you might see ram rated at 3-4-4-8@275mhz. this is the 4, in than situation.

2 yeilds the best performance, and 4-5(5 is usually overkill) yeilds the best overclock. Most rams will not be able to use 2, and reach there max OC

**Row Cycle Time(tRC)**= 7-22 in 1.0 increments.

7 yeilds the best performance, 15-17(i think 17 is overkill) yeilds the best stability/overclock. i would start at 15, and work your way down from there. Also, 7 is usually much to tight, for most ram.

**Row Refresh cyc time(tRFC)**= 9-24 in 1.0 increments.

this timing is usually always set to 2-4 clocks higher that the tRC.

10 yields the best performance(well 9 would, but 9 is to tight), and 17-19(i think 19 is overkill) yields the best stabiltiy/overclock. i i would start at 17 and work your way down

*Row to Row Delay(also called Ras to Ras delay)(tRRD)*= 0-7 in 1.0 increments.

00, or 2 seems to yields the best performance, and 4-6 yeilds the best stabiltity/overclock. i know that 00 sounds odd, but it works great for me, even at 260mhz

*Write Recovery Time(tWR)*= 2, 3

2 yeilds better perfomance, and 3 yields better stability/overclock.

*Write to read Delay(tWTR)*= 1, 2.

1 yeilds better perfomance, and 2 yields better stability/overclock.

*Read to Write delay(tRTW)*= 1-8 in 1.0 increments.

1 yeilds better perfomance, and 4(i think any above 4 is overkill) yields better stability/overclock.

**Refresh Period(tREF)**=

1552= 100mhz(?.?us)
2064= 133mhz(?.?us)
2592= 166mhz(?.?us)
3120= 200mhz(?.?us)(my sweat spot w/ Bh-6 at 250+mhz :cool: , your mileage may vary)


3632= 100mhz(?.?us)
4128= 133mhz(?.?us)
4672= 166mhz(?.?us)
0064= 200mhz(?.?us)


0776= 100mhz(?.?us)
1032= 133mhz(?.?us)
1296= 166mhz(?.?us)
1560= 200mhz(?.?us)


1816= 100mhz(?.?us)
2064= 133mhz(?.?us)
2336= 166mhz(?.?us)
0032= 200mhz(?.?us)


0388= 100mhz(15.6us)
0516= 133mhz(15.6us)
0648= 166mhz(15.6us)
0780= 200mhz(15.6us)


0908= 100mhz(7.8us)
1032= 133mhz(7.8us)
1168= 166mhz(7.8us)
0016= 200mhz(7.8us)


1536= 100mhz(3.9us)
2048= 133mhz(3.9us)
2560= 166mhz(3.9us)
3072= 200mhz(3.9us)(working Great so-far for my CT-D5)


3684= 100mhz(1.95us)
4196= 133mhz(1.95us)
4708= 166mhz(1.95us)(alot of people seem to use this for TCCD's)
0128= 200mhz(1.95us)

I suppost that the tREF, like the tRAS, is not an exact science. it seems that the 15.6us, and 3.9us settings seem to work good, and that the 1.95us settings give usual results(extremely low bandwith for me)

the unknown (?.?us) are kinda shot in the dark, for me, out of all the setting 3120 gave the best balance of performance, and stabiltiy, but i feel this will greatly vary from one ram to another

Write CAS# Latency(tWCL)**= 1-8.

I can only POST using "auto", and 1. Both Give the same bandwidth, and stablity If you have had any success with this timing please post here.


*DQS skew Control*= Auto, Increase Skew, Decrease Skew.

Little is known about this timing, but use Increase for performance, and Decrease for Stability. The best way to find out what is best for your system, is trial and error.

*DQS Skew Value*= 0-255 in 1.0 increments.

This is the value that is Increased or Decrease when you set the DQS skew control. This is not a very sensitive timing I would try 32, 64, and 128. Trial and error here to

DRAM Drive Strength**= Level 1-4.

I would only suggest using Level 1 or 2, if you have CPC enabled.(although every sysem will react differently, and it is best to try them all) With CPC, anything above level 1 gave me extreme instablility, some reported that level 2 or 3 work good with CPC enabled, although this didnt work for me. Some otheres have had success w/ using level 2-4 if CPC is disabled.

*Max Asynce lantency**= 00.0-15.0 in 1.0 incements.

I would suggest trying 5.0-10.0 depending on your ram. 5ns will problobly not allow much overclocking, and 7-8ns is usually the optimal

*Read Preamble time*= 02.0-09.5 nano sec, in 0.5 increments.

I would suggest 4.0-7.0 depending on ram. 4ns will probobly not allow for much overclocking, and 5-6ns is usually the optimal

*Idle Cycle Limit*= . 000-256 in varied increments.

I would try 16-64 clocks. usually this doesnt affect overclock that much, but i found that sometime at exteme buses( ie 290+), that moving to 32-64 clks added some stability

*Dynamic Counter*= Auto, Enable, Disable.

Enable for slight bandwidth increase, Disable for stight stability increase.

*R/W Queue Bypass*= 2x, 4x, 8x, 16x.

I would suggest using 8x or 16x for max performance, and 2x-4x for max OC.

*Bypass Max*= 0x-7x in 1.0 increasments.

I would suggest 5x-7x for max performance, and 0x-4x for max OC.

*32 byte Granulation= Auto, Disable(8burst), enable(4burst).

Try Enabled(4burst) for more stability, and Disable(8burst) for more bandwith.

jmke 7th November 2004 03:09

Genie bios Settings

Dram Configuration=(see above post)


FSB Bus Frequency= 200-456mhz in 1mhz increments, this is what is commonly called HTT(most know it as FSB)

Agp Bus Fequency= 66-100mhz in 1mhz increments. it is not neccasary to set to 67mhz to get a pci lock, like on other NF3 mobo's, but it wont hurt to do it, just for safety

LDT Downstream width= Auto(16bit), 8bit. i would suggest leaving on auto for best perfomance

LDt Upstream Width= Auto(16bit), 8bit. i would suggest leaving on auto for best performance

LDT/FSB Frequency Ratio= 1x, 1.5x, 2x, 2.5x, 3x, 4x, 5x. i would only suggest using 5x for use in combo w/ 200mhz HTT. Try 4x up to 235-245. 3x up to 245-265. and 2.5x from there on up. if your going for max HTT(like something over 300-350) try 2, 1.5 and 1x.

CPU/FSB Frequency Ratio= 4x-20x in 0.5 increments. THis is your CPU multipier(multipy this times your FSB Bus frequency to get you cpu frequency. i would suggest NOT using 4x, or 0.5 multis, because this puts your ram on a ratio. you may only us your stock multi, and lower.

K8 Cool 'n' Quiet Support= Auto(enable), disable. Mobo automaticly scales down VID/FID at system idle. DISABLE for overclocking!!

CPU VID Control=
0.800v-1.550v in 0.025v increments. VID means Voltage IDentification. This is simple the Vcore.

CPU VID Special Control= 104%, 110%, 113%, 123%, 126%, 133%, 136% above VID. you multipy this by CPU VID control to get your total Vcore. (113%=1.13, 104%=1.04)(so if Vcore is 1.55, and specail is 110% you would have 1.55v x 1.1=1.705v)

Chipset Voltage Control= 1.6v-1.9v in 0.1v increments. i would recomment up to 1.7v on stock passive air cooling on the chipset... up to 1.9 w/ active cooling, and perhaps a better HS...

AGP Voltage Control= 1.5-1.8v in 0.1v increments.

Dram Voltage Control=
2.5v-4.0v in 0.1v increments. This bios gives opions to go UP TO 4.0vdimm, NOTE:you must mod you 3.3vrail to use anything above 3.2v. your 3.3v rail must be 0.1-0.15v above the selected Vdimm.(ie for 3.5 vdimm you would need 3.6-3.65v 3.3rail)

jmke 7th November 2004 03:11

3 Attachment(s)
A64 MEM:HTT ratio - Clearing out the Dividers Mess - Another nifty table

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