PDA

View Full Version : Overclocking- what is "safe" and what causes processor degredation the most?



wacom
07-14-2009, 11:44 AM
I asked for some advice on a new system based around the Phenom II x4 955 processor vs. the i7 and went for the AMD solution. Both are great and each has it's advantage for sure, but I needed the extra cash for nicer fans, heat sinks etc.

I'm very happy with my purchase over all and the system has exceeded my expectations so thank you to everyone that helped me.

Now I've unfortunately been tempted into the world of overclocking since my MB and processor just seem to beg to be overclocked.

I've managed to get a very stable system running with a core clock of 3.8+ with roughly 1.49 core volts and at a reasonable temp. So here is my question:

The max temp listed by AMD for this processor is 62C and I can OC and keep it around 55C full load (ambient temp was ~28C at time of test). The standard voltages are rated from 1.35 to 1.5v and I've had it OC to 1.49v.

Is it safe to run it at these temps and voltages if everything is stable (prime95 and render stable) and cool enough? I keep my systems/components for 3-5 years. These seem to be in the stated "saftey" zone by AMD and resellers. Or am I voiding any warranty by using such voltage even though they say it's within the "normal" range? Is it the heat or the voltage, the frequency, or what that helps degrade the processor or all of them?

Sorry- I just can't seem to find any answers on the web for OCing that's "reasonable" only for OC that's over the top or pushing it pasted the stated "safe" voltage.

Right now I'm actually under volting it to 1.265v and still running it at the normal 3.2Ghz- load temp is 46/47 with fans at ~50% speed (my wife hates a noisy computer).

Thanks-
Gideon

Ernest
07-14-2009, 02:11 PM
Definitely voltage. The temperature can degrade the processor but it has lots in built-in safeguards for that so in practice it's not a major factor. Voltage is the big one.

RebelHill
07-14-2009, 02:31 PM
voltage is the most damagin for sure... but pushing the heat threshold over time will be just as bad, and surprise surprise, manufacturers dont really post their tolerance limits.

Best bet is to keep upping ur processor speed by the smallest possible increments, lil by lil... and run it at 100% for about an hour... when it starts to become a lil flakey/bluescreen on you, take it down about 2 notches from that max, and you should be safe there.

wacom
07-14-2009, 02:49 PM
So...if they say "voltage 1.35-1.5" does that mean it's fine to run it in that range so long as you don't get the temps above the stated 62C?

Why would they give such a large swath of voltage if it isn't "safe"?

zapper1998
07-14-2009, 04:16 PM
So...if they say "voltage 1.35-1.5" does that mean it's fine to run it in that range so long as you don't get the temps above the stated 62C?

Why would they give such a large swath of voltage if it isn't "safe"?

that also ties into the memory voltage to...
Heat is the biggest culpret of damage to CPU's
the cooler the better
with 4 or eight cores you really do not need to OC them
The KEY is to keep them COOLER. The Cooler or colder you run them the harder they can run..
My dual core I have it running at a avg 44 to 48 deg F, with 2 huge Coolers
Mind you i have to clean the buggers every other month...

Andyjaggy
07-14-2009, 04:19 PM
I'll take a 5% increase in stability over a 20% increase in speed. :) but I know most people don't share my thoughts on this matter.

That and I just have no desire to dick around with voltage settings for a week to get it reasonably stable.

wacom
07-14-2009, 04:54 PM
That's just the thing- the system is "crazy easy" to overclock and keep stable for hours. The main thing I'm looking at is the main processor clock speed as memory speed has very little effect on most software based rendering. CPU clock speed though has a huge impact on render speed (which we all know).

That said, I found that if I have crashes during render...sometimes lowering the speed of the RAM helps while only ever so slightly effecting performance (we're talking less than 1/2 a %).

And yes- my chip supposedly has a cut off...but because it's a "BE" addition it will not down step unless it gets to a very high temp. I unfortunately discovered that when like the computer builder noob I am, installed two intake fans and the main heatsink fan facing the wrong direction! YIKES- 70c temps! Needless to say I shut it down REAL fast at that point! Can you say idiotic?

Anyway- what that means is that unless it becomes unstable- heat doesn't effect performance as much for this chip AFAIK- it doesn't auto regulate as much a some is my understanding...not sure if that's a good or bad thing...and maybe I'm wrong?!

Maybe this isn't worth it...but it's so tempting!

JonW
07-14-2009, 10:39 PM
Over clocking is not safe & you do it at your own risk.

Having said that, a CPU is a disposable product, it only has a economical working life of two years at best, so thrashing it to death is probably the best thing to do.

There is a balancing trick between; what is the CPU & the reliability of your system worth to you, compared to the extra Ghz you gain & the money you spend to gain the extra Ghz.

Rather that buying extra heatsinks & various parts for the box. It may be better to add another cheap box in 12 months instead of waiting 3 years.

I would leave your CPU at 3.8, you said it was stable, if you get, say, 4.0 out of it. A one hour render will now take 57 minutes. To me this is not worth the money or the mucking around.

Another box in 12 months will give you over twice the rendering resources.



Cost per frame output per each of my whole system set-ups as a percentage of the most economical box.

i7 920 100% efficiency
i7 940 95%
5580 V8 54.6% (theoretical)
5450 V8 49.5%
5335 V8 47.6%
Mac Mini 39.7% (2.0 Ghz. Replace ram & HD)

So in other words if a frame on my 920 costs $1.00
940 $1.05
5580 $1.83
5450 $2.02
5335 $2.10
Mini $2.51


My 920 & 940 are bare bones boxes with no redeeming features, just built for rendering. (but the 940 @ 3.5 Ghz bakes radiosity about 30% to 50% quicker than the 5450 V8)

wacom
07-14-2009, 11:28 PM
OK, good point. Besides, I will not have to buy a new box, just a new chip and maybe a new MB to see better render times...I went this route because I was sick of throwing everything away and starting all over all the time when it wasn't needed and only cost more money. Besides- my software expenses are 6X that of my hardware costs.

I'll leave it too the OC hobby crowd for now...maybe I'll see how far I can go for fun...but then take it back down to normal speeds.

The latest generation of quad cores really does blow the doors off my old Pentium D so I should be happy with what I have- and it's very stable (much more so than my old system).