Kt7a FSB overclocking (>133mhz) Instability

[jcadence]

Hi, I am running a Athlon T-bird 1-ghz on an Abit Kt7A, running stable at a FSB of 133 mhz (either 1000 or 1133). I am using Micron/Crucial Pc133 cas2 ram. When I set the FSB a bit higher, to 135-140 mhz, using Softmenu and the "Cpu FSB Plus" setting, my computer will freeze a few seconds after startup, or while doing some task; then, when I restart, there may be a "Bio rom checksum error". I'm wondering if there's any way to achieve stability while at FSB speeds above 133.

<Other info:>
Win98 Se
All-in-wonder Radeon AGP
SB Live x-gamer
Latest Kt7a bios and Via 4-in-1 Drivers
Thermaltake Volcano II Cpu cooler and 2 case fans

Bios:
Cpu voltage: 1.85
I/o voltage: 3.5-3.6
Force 4-way interleave: Enabled
Enable Dram 4k-page mode: Enabled
Bank Dram timings: Turbo
Sd ram clock cycle: 2
Dram ban interleave: 4-way

I think the Kt7a with Crucial Pc133 ram should be able to achieve a higher stable Fsb overclock than 133 mhz (even if the overall clock is between 1000 and 1133 mhz)..how can this be achieved? Any help appreciated

 

[WarCon]

I have a KT7A and I can't get any FSB over 139 to be stable even if I am underclocking the processor. I think is might be the Northbridge chip. My hsf on the northbridge was highly concave, but lapping it hasn't seemed to help. I am moving to an Iwill or and Epox(if I want to sell my Crucial PC133 and get DDR).

 

[dew042]

i see a couple of issues:

cpu voltage: 1.85

probelm: default voltage for 1ghz is 1.75v. only increase it after you get it stable and overclock more. in my experience its only neccesary after 200mhz or so of oc.

i/o voltage: 3.5-3.6

probelm: my kt7a doesn't need a voltage increase until a 150mhz. standard voltage is 3.3v. set it back.

go up slowly and when you run into probelms reset the cmos and try uping the voltage the cpu and as you get up to 145-150mhz FSB you may have to start uping the i/o voltage. you have to methodical and follow some formula. random changes won't work.

be sure to visit the kt7 faq, its excellent: http://www.viahardware.com/faq/kt7/kt7faq.htm

good luck.
dew.

 

[jcadence]

I lowered the voltages..doesn't seem to help. 34-35 C system temp, as reported by Via-Hardware-monitor isn't too high, is it?

 

[Rafael]

These temps seems fine. But these temps are when you are running om 133 Mhz? Or when you got it OCed?

Raf

 

[MrThompson]

My system temps stay within 1C of ambient. Your settings and ram don't seem to be the problem. The key to getting FSB on a poopy KTA is case cooling and a better HSF on the Northbridge. I picked up 1 MHz of FSB by adding a HS to the clock generator.

Older KT7As don't do as well at high FSB. If your board came with WW BIOS, the odds are it is an older board.

 

[optimistic]

I can run my ABIT KT7A at 148fsb.

(9x148) = 1332MHz no problems.
1.75 Vcore

But I can't seem to run at any other speed.

 

[SiLow]

I can't even get my KT7a to run at 133!!!! WTF is up with that? I can't figure out why it won't run at 133. It stalls at the memory check (I have PC150 RAM so it can't be that can it?) Anyone know why? And when it does pass the memory check, Windows (98SE) gives me a Registry Error. WTF, this KT7a is pissin me off.

 

[MCS]

My KT7A was useless for overclocking the FSB, I got more than 135Mhz though. Would run 140Mhz stable, and I could just about get 145Mhz if I raised the I/O to 3.7V...150Mhz was not possible. I changed to an IWill and got 150Mhz stable straight away, same componants. Just goes to show.

Try using different multipliers if you can. I used to get the freeze at desktop error but I tried different multipliers and different FSBs and it would suddenly work, even if the resultant CPU frequency was the same!

 

[SiLow]

Yeah, but I even tried underclocking by locking the L6 bridges to a default multiplier of 7 so I got 931mhz(7x133) and it still got registry errors.

BTW, I'm not even looking to overclock the FSB, I just want 133 plain and simple.

 

[SnowPunk98]

im havin the same kinda problems I am workin on fixing them got a 1.1Ghz trying to get 10x133 seems impossible

 

[jugornot]

Are any or all of you using a usb mouse or other device? Seems usb is very oc unfriendly. Try usinf ps2 mouse and see what happens. Just an idea.

 

[jugornot]

Also abit has released a new beta bios that is supposed to increase stability at high fsb. HTH