Help me push my overclock a little further. AMD

famas

famas

famas

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Hello all

I recently build a new pc and decided I would like to give overclocking a go.

I've been reading a lot over the past few days trying to understand the basics involved with small overclocks.
To be honest not a lot has sunken in, theres a lot to learn and trying to find simple anwsers trawling through hundreads of threads and forums can be frustrating.

But with limited knowledge I have achieved my first small over clock. yay! :)

My spec is
Asus m4a785td v evo
phemon 550BE
4GB G.skill ripjaw 1600MHz

And my first overclock is to 3500MHz


As I understand overclocking is made very simply on these processors because of the unlocked multiplier, which indeed it is.
To achieve 3400MHz All I did was raise the CPU multiplier to x17 every thing else was left on auto and the system was perfectly stable.

Pleased with this I tried to push a little further upping to 3500MHz (x17.5)
again every thing else left on auto.
Windows loaded fine and I ran prime95 for 20 mintues or so with no problems or errors.

With this result I tried going one step further to 3600MHz (x18) and this is where things get tricky.

Every thing was left on auto excpet the CPU multiplier which was set to x18.
Re-started pc and got my first BSOD at windows login.

I then went back to the bios and gradually increased the Vcore a step at a time. I had to push it to 1.37500v befor it would load into windows and run prime95 without crashing straight away.

Again gradually increasing the Vcore and running prime95 after each increase I went up to 1.40000v but could not get the system stable when running prime95, It would BSOD sometimes after 10 mintues other times after an hour.

question 1
At 1.40000v I stoped as I do knot know what a safe Vcore voltage is for this processor???

question 2
I've read that it is sometimes necessary to increase the CPU-NB (VDDNB over-voltage) voltage aswell as the Vcore voltage to get things stable. I have not tried this yet as
1 I dont not know what the stock voltage for this is, and 2 I dont not know what a safe voltage to go up to is?

With this failure I droped the CPU multiplier back to x17.5 with every thing else back on auto. I ran prime95 but got a BSOD after two hours.

Again I gradually increased the Vcore a step at a time untill 1.36250v where I ran prime95 for 8 and half hours with no crashes or errors.

Screen shots of this.

screen01uo.jpg


screen02z.jpg


On this clock I also got 4185 on fritz chess benchmark, I have no idea if this is good as I have nothing to compare it to.

One thing I did find strange is that I set the Vcore to 1.36250v in the bios but both CPU-z and AMD overdrive showed a maximum of 1.31200v is this normal?


I'm pretty happy with this overclock for my first ever go, but I feel its got a lot of room for improvment and would just like some advise on what settings to fiddle with and what a max safe value would be for those settings.

any help is greatly appreciated.

cheers.
 
Question 1: The max vcore is 1.5 so you are actually operating with very nice low voltages.

Question 2: I believe the rule for cpu-nb frequency is that it should be at least 3 times the memory base frequency. So for you that will be 2400. This will be a 12x multi in the bios for cpu-nb. You should not need much of a cpu-nb voltage increase to get this stable (if any) but as with any setting change test with prime to make sure. The max cpu-nb voltage is 1.5 as well. But I would be supprised if you needed above 1.35 max.

Other advice: Set your loadline calibration to 16%. That will help with stability.

Keep going as you are going. Icreasing the vcore a little at a time to get it stable. Most people find that the sweet spot with these chips is around 3.8GHz (18x multi) after that you need large vcore increases for small performance boosts.

Have you tried unlocking your chip?
 
Hi eddyc, thanks for your reply.

I'll try getting it stable at 3600 again with slight increases to vcore the cpu-nb voltages.
I'll also try changing the cpu-nb frequency to 2400 (x12) and see if thats more stable.

What is the load line calibration, and what does it do?

I have tried tri and quad on this chip with vcore up to 1.4 and cpu-nb to 1.35 and +2 value on cores 2 and 3, thought I dont know what that does?
cant get the system to boot though.
is there any thing else I can try?

thanks again for your help, I'll let you know how I get on.


EDIT: just had a look at the load line calibration and there is no 16%
there is a x16 .125% is this what you mean?

cheers.
 
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update.

possible success at 3600MHz

CPU-NB frequency= 12.00x
Vcore= 1.40625
CPU-NB voltage= 1.21875

How do these look???

I've left the line calibration at auto as I'm not 100% sure what it should be set to.

CPU-z and overdrive are still showing incorrect Vcore. Both showing 1.374 even though I've set it to 1.40625 in bios?

Core temps are holding steady at 35c
CPU is holding steady at 40c

been running prime95 blend for over an hour and a half and all good so far. I'll leave it running untill late tonight, hopefully with no crashes.

If all goes well I'll try for 3700-3800MHz tomorrow.
Its quite addictive this overclocking malarky :)
 
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I think to be honest if you have tried unlocking with those settings and it has not worked then you have probably just been unlucky. I dont think there is a huge amount you can do.

Those other settings look good. Lets see how it goes.

Oh with loadline I actually meant 19% sorry. It will be 19.xxx% cant remember the exact number.

The loadline calibration deals with vdroop which is when the vcore lowers slightly as load increases on the chip (this can cause instability).

The lower vcore in cpu-z than set in bios will be due to vdrop and vdroop. vdroop can be eliminated (mostly) with loadline calibration and I dont think there is much to be done about vdrop but it does not really matter.

Those temps look very good. Fingers crossed.

Not sure if you are already posting in the Phenom overclocking thread (over in the cpus section) but it would be good to post your results there. Lots of people will be able to advise you on the next steps. But to be honest it sounds like you have the hang of it.

Just dont exceed 1.5 vcore and dont let temps get into the high 50s.

Also do you have cool'n'quiet turned on? I would keep it off until you have a stable clock you are happy with and then try turning it on. It helps A LOT with idle/partial load temps though it might (unlikely) cause instability.
 
@ mattjd, Yes have tried to unlock the cores with no success :(

thanks again for all your help eddy. If this clock turns up stable I'll stick some screenies in the phenom thread.

cheers for the info on the loadline calibration, I think it will be needed when I try for 3800MHz

thanks again.
 
just after posting this one of my cores droped out of 100% when running prime95, I take it this is a stability failure? Prime didnt bring up any errors though?
 
What so the core just dropped down to 0% usage but the system did not crash and prime did not fail...?

Odd. I have never heard of that. I think best post in the phenom thread with that one. :D
 
yeah, after about 2 and a half hours core 1 dropped to 0% then would go up to around 7% then drop back to 0% and so on never going back up to 100%
while core 0 stayed at 100% the whole time.

I'll stick a post in the phenom thread and see what comes up.

cheers.
 
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