Using Prime 95 for stability

I was wondering which option do you use when testing for system stability in Prime 95....under the Torture menu:
a) Large FFT
b) Small FFT
c) Blend
d) All 3 of the above

I can get my system to run the Blend tests, but I usually get an error (usually round off error) within the first 5 minutes of the other 2 torture tests - Large FFT always under 1 minute.....

Can anyone help me out on this?

Thanks in advance

Well first of all, if you have errors, then it is not stable. You should be able to run all of the tests without errors to be fully stable. Different tests stree different components. The round off error probably means an unstable processor clock.

And that means what? Increase voltage?

Means increase whatever it takes to make it stable, vcore, chipset, agp volts,, dram speed and timmings, cooling.....

rb

Overclocking is a combination of everything. You will learn as you go. Most important things are your components. So, if you want us to help you more efficiently, please post the spec of all your components. Also, we need to know the stepping code of your processor also.

Let us know your spec, and we shall see what we can do for you.

Papsomax said:

Means increase whatever it takes to make it stable, vcore, chipset, agp volts,, dram speed and timmings, cooling.....

rb

Click to expand...

AGP volts to make a CPU overclock stable ... ? Let's not just throw tons of terms out at him that won't help.

Increase your core voltage (vcore) and keep an eye on your temps. You may also need to adjust your chipset voltage (also referred to as the VDD and the NorthBridge voltage) and/or your ram voltage (vdimm).

Generally, you need more volts to the part that is unstable, so if it's your ram causing the problems, it needs the raised volts more than the CPU. And vice versa if the ram is stable but the CPU isn't.

It's a lot of tweaking and re-checking. Just make sure that while you test one component (such as the ram by setting a high FSB speed), you lower the multiplier for your CPU so that your whole system isn't overclocked ... that way if you get errors, you'll be able to pinpoint the cause of the errors, instead of having to guess if it's because your FSB is too high, or your CPU is trying to go to fast on too little volts, etc.

I run the Blend test most often, but I like to run the Large FFTs to see how hot my CPU is getting, too. When leaving it running for longer periods to test stability, I typically run Blend, though. At least until it's stable ... then I move on to another test.

- Dave

Ok, well here's some of my specs:

1) using MBM:
a) Core 0 = 1.63V
b) Core 1 = 2.61V
c) +5 = 4.95V
d) +12 = 11.8V
e) -12 = -12.19V
f) -5 = -5.24V
g) 3.3 = 3.31V

cpu = 2500+ Mobile Barton @ 2.424 Ghz
Mb = Abit Nf7-s rev 2
ram: 2x512Mb Corsair 500 Mhz
HD : 2x 36Gb Raptors
1x 40 Gb
hs: sp-97 with 92mm at 48 cfm
video: Radeon 9800 Pro
ps: Enermax 550 W
case fans: 2 rear blowing out
1 top blowing out
1 side blowing in
(ps: 92mm blowing out)
*Case fans are still being set up - have post in cooling section

cpu is at 220 x 11 @ 1.675V vcore
temp of cpu: idle = 35 celsius
load = 30.5 celsius
(AC is on - case temp is 25 celsius)

Ram is at default settings (something like 3-3-3-8)

as for the cpu stepping......don't know.......can't check because it's installed and don't know how to install/remove cpu/heatsink and don't want to with these kind of parts installed - blew a ps already...........

Hope this helps some more to be able to help me some more....

Oh, by the way: Blend test ran 12 min before i stopped it; small and large FFT caused errors within several seconds....

Anybody???.....

it looks like you should try upping the vcore.

try 1.75 vcore in bios, i'm sure that that will prime.

also, you might want to up the ram voltage .1 - .2.

the nf7-s really doesn't seem to like cas3 operation and i'm surprised you can even boot.

i believe you should be able to tighten up that up to cas 2.5 on that ram below ~235 fsb, so you could try that. at cas 3 the memory bandwidth is really going to suck, and i doubt you will be able to get upto 250 fsb on a stock nf7-s (unless you are sentinnel of course )

anywho, up the vcore and ram voltage, and try to tighten up those timings.

hope this helps

Already went and tried with 1.7, and 1.75 and 1.8V - still no luck... Changed the Ram voltage to 2.7 (from default of 2.6)..no luck....I will try lowering the cas to 2.5 next....

You think it's ok to increase the ram voltage to 2.8?? Don't have any temp monitor on that....nor the chipset...

For some reason if I use 200 fsb it'll boot and be stable with 11 and 12 (only i tried) cpu multipliers...although 200x12 runs at 40 celsius idle and 46 load in prime95 running large FFT...

Just increase the ram voltage to 2.8 if that doesnt work then do 2.9v

2.9v is fine for most memory.

If its still unstable then raise the cpu vcore toe 1.85v. As for youre temps thier perfectly fine.

Ok, I got it stable at 221x11 @ 1.75V with ram @ 2.7V and the ram settings at 8-4-4-2.5

It turned out that having the cas on the ram at 3 was the problem...put to 2.5 and now it's stable.....

I even went up to 221x11.5 @ 1.8V and other settings the same, but the Blend and Large FFT tests fail within 5 min....i want to try again later by increasing the ram voltage to 2.8V and maybe 2.9V....first i need to install new fans and get everything done with that because my case temp is jumping to 28 celsius from 25 at these settings.....cpu jump to 48 celsius from 40...


Does anyone know how good the chipset cooling is on the Abit NF7-S rev 2?? It's got the default fan on there now....should I change that??

i think that the L12 mode will help also remmenber to cool your south bridge (220+fsb)
you dont need to up the voltage for your memory as i see you have ddr 500 pc 4000 mean that your will do 250 fsb without probleme
so
1) l12 mode
2)cool your chipset (south bridge , [north --if possibe--])
3)higher chipset voltage ,and cpu voltage
4)better cooling for the cpu
5)relax memory timing

What's the l12 mode?

I'm already planning on getting southbridge cooling...and i think i'm gonna replace the stock northbridge (NF7-S rev 2) - then I'll up the voltage on the chipset....

How do i relax mem timings? use larger numbers? ex rather than 8-4-4-2.5, use 8-5-5-2.5?

Yes, to relax your timings bump them up a notch. Just like your example.