Overclocking Question

[planetgong]

Hi guys and gals just a quick question.

I am just in the process of overclocking my Opteron146. I can get the chip to go to just under 3GHz if I set a really low ram divider. However when I increase the divider to increase the RAM speed my system crashes.

Is it better to get the highest CPU speed and run the low divider, or just get the best overclock my memory will let me?

I had to put 1.65v through the CPU to get it near 3GHz. Is that too much? It was idling at 31c and was about 38c under load.

Thanks.

[sgoaty]

what is your ram running at? try not to have it to much below stock. 1.65 is a touch high but it should be ok. What cooler are you using?

[planetgong]

what is your ram running at? try not to have it to much below stock. 1.65 is a touch high but it should be ok. What cooler are you using?

Big Typhoon. Its pretty damn good I have to say! So is the CPU speed more important than the RAM speed as long as the RAM is running around stock?

[Rohan]

Yep, CPU speed is most important. RAM speed is of less importance, although RAM timings can have an impact.

[Dark Horse]

Cpu speed is much more important than ram speed. If you can overclock your ram aswell thats always a bonus but if it was a choice between the two I'd keep the ram at stock through a divider and the cpu overclocked.

If you are a superpi loving benchmarker then you still get the cpu as high as you can and then work the ram up to as close to 1:1 as possible.

[planetgong]

I've currently got my system to this. Any higher and it seems to crash in Prime95. I have tried upping the vcore and that doesn't make any difference, so I think this could be my max!

(Not sure how to upload a screenshot)

CPU @ 280*10
Memory on the next divider down from 1:1 (233.3MHz) 2.5,3,3,7 1t
Temps is 26c idle, 31c under load.

[Dark Horse]

By crash prime95 do you mean bsod or just errors? A basic test of system stability would be to run prime95 for 12-16 hours. If you get no errors then it is likely to be stable.

OCCT is a good short test, only takes 30mins so isn't as comprehensive as a long prime session but is still worth a try to see if it is worth doing a long prime.

[iranu]

What voltage is your ram running at? Usually it's between 2.6v-2.8v. Upping it to 2.8v won't be a problem. Usually makes it more stable

Does your motherboard have options in the Bios to go higher than 2.8v?

[5aboy]

1.65V for the CPU is waaay too high - the opterons have a slightly lower vcore than the athlons to begin with, and unless you are cooling with water, then you will damage your chip.

i can also assume that you have high temps with this, which is not good for the chip.

ram voltage should be set at 2.85V max (unless you know you got bh5 and your mobo allows 3+V )

hope this works out for you!

[sgoaty]

Its quite high but if his air cooler is keeping the temps below 60 under load then it will be fine

[planetgong]

My temps are 35 under load and 28 when idle! So they are still very low.

Dark Horse - prime just stops after 10 seconds or so and cannot continue.

iranu - I have tried the RAM at 2.7 & 2.8 and it makes no difference. My board will go higher if I want it too!

[Dark Horse]

Dark Horse - prime just stops after 10 seconds or so and cannot continue.

If your computer just crashes when prime runs then you have definately gone too far. Prime will stop after one error on a slighly unstable computer but it will not crash your computer unless completely unstable.

Look at this guide here
http://www.dfi-street.com/forum/showthread.php?t=20823

Specifically:

Finding the max of your CPU\RAM

Finding the max of each component is very important in overclocking. Many people think they can just up the HTT and be done with it, but that’s not true most of the time because then you might get instability and not know what the source is. To me, not finding the max of each component is like fighting a group of people at once when you have the option to fight them one at a time. The first thing I like to do is find the max of my CPU and then my ram.

To find the max of your CPU you want to take out your other components as variables, so this is what I do:

CPU/FSB Frequency Ratio (CPU Multi) to default. Do NOT use the auto setting! Manually set it to whatever your default multi is.

LDT/FSB Frequency Ratio (LDT Multi) to 2.5x or 3x.
Setting this lower right now will make sure that your total HTT speed doesn’t cause instability.
Quote:
Originally Posted by Wildstyle
You are freely able to lower this value and not lose performance because even with a HyperTransport Bus frequency of 200MHz (LDT = 1x), due to the nature of the HT architecture, there is still enough bandwidth available to transfer data between CPU/RAM/HDD without bottlenecking; and at 200MHz the theoretical bandwidth limit is still higher than that of AGP 8X, so video card performance is not affected either.

LDT/FSB Frequency Ratio (Ram Ratio) to 100(Mhz)(1/02)
This is much lower then you should ever set this but it will make sure your ram is running way under spec and wont be causing you any problems at this point..

CPU VID (Voltage Identification) Control (CPU Vcore)
This is a tricky one.. Its gonna depend on how good your temps are and how far your willing to take it. For 90nm cores (i.e. Sandiego, Venice, x2, Winnies) its best to stick around 1.6v-1.65v MAX, For 130nm cores (i.e. Clawhammer, newcastles) you can go a little higher to 1.7v-1.75v but always make sure temps are good. If you have extreme cooling like water or phase then you can take the voltages higher. You could also try to see how far you will get on stock vcore first or just bump it up from the start. This is totally up to you and what you feel comfortable with. Some A64 CPU’s actually overclock better with less voltage that’s why its good to start off lower to find the max of that and if your unhappy or want more then you up it from there.

**Important Note**
Load is when your CPU usage is at 100%. This will happen while playing games and also when running the stability testing programs I listed above, especially OCCT and Prime as they will make your CPU usage 100% for sure. Load temps for CPU’s should always stay at or below 50c, a little over 50c wont hurt either but lower is always better.. If your temps are exceeding 50c by a lot then you either need to upgrade the cooling or lower your voltages and\or clocks.

Ok.. now that you lowered the LDT multi, put your ram on a ratio, set your default CPU multi manually and decided what vcore you want to start with its time to start testing..

You want to start raising your HTT\FSB in 10-15mhz increments and in between each move you want to boot into windows and run the SuperPi 32m test. It will take about 30-45 mins normally. If it passes that then keep upping the HTT until SuperPi gives an error then back it down a few MHz (1 or 2) at a time until its stable again...

**Remember to monitor temps**

Once you find the highest spot where SuperPi is happy you want to run the OCCT 30min test (Not the torture option.) This test is a little tougher then SuperPi and if OCCT fails then lower your HTT\FSB 1 or 2mhz until you can pass OCCT..

**Remember to monitor temps**

At this point you can run each 3dmark bench to see if they complete without a crash or error. Don’t worry about the scores being low, this is because we slowed everything else down except the CPU.. If they all pass then we are off to Prime time.. hehe. This is the last thing you will run to test the stability of your CPU . Many people are going to have their own amount of time they like to run prime. Personally I run it for 8-10 hours but some like to run it 24 hours before they consider their system stable. I can understand running it for 24 hours when you’re comparing between peoples stable clocks to make sure they are all stable with the same guide lines but I never felt the need to run it that long for my rig to be stable for ME..

If prime fails then back off on the HTT/FSB some until it passes at least 8 hours without errors.

CONGRATULATIONS !!
You just found the max mhz of your cpu..

Next thing we are gonna work on is finding the max of your ram.. Here is how you are gonna setup for that:

CPU/FSB Frequency Ratio (CPU Multi) This we are going to lower to the 7x multi.

LDT/FSB Frequency Ratio (LDT Multi) Keep this at 2.5x or 3x just like it was when testing the CPU..

LDT/FSB Frequency Ratio (Ram Ratio) Put this at 200 (1/01) so it will be running the same speed as your HTT now.

CPU VID Control (CPU Vcore) You can leave this at the same setting you decided to leave it at during your CPU testing.

Now you have the CPU vcore like it was during the CPU testing, the CPU Multi to 7x, the LDT Multi to 2.5x or 3x, and the RAM ratio set to 200 1/01..

There is only one more thing that you need to do before testing the ram: Learn about timings!! I’m not gonna go deep into this but I’m gonna suggest what timings are popular with some known types of ram chips. Before you go ANY further I highly suggest you read this ram guide by johnrr6 at DFI Street..

http://www.dfi-street.com/forum/sho...179&postcount=4

Its also a good idea to do some research to find out what type of chips your ram use.. It will give you a better idea where to start off with timings and voltages.. Here is a link that might help you find what chips are on your sticks of ram..

http://xtremesystems.org/forums/showthread.php?t=50010

Here are some timings I can recommend without getting deep into the full page of memory timings that my DFI board has.. hehe

TCCD
CPC- Enabled ( 1T )
Cas- 2.5
tRCD- 3 or 4 for more stability
tRP- 3
tRAS- 8

BH5,BH6,VX,UTT
CPC- Enabled ( 1T )
Cas- 2
tRCD- 2
tRP- 2
tRAS- 8

No matter what ram you have timings are never written in stone. They NEED to be tweaked, period ! Always remember that just cuz “Joe Overclocker” says his TCCD runs at 300htt with 8-3-3-2.5 timings doesn’t mean yours will even if it’s the same ram brand, model, revision, production week.


Time to start testing your RAM !!

With the above settings you want to start raising the HTT\FSB 5-10mhz, and in between each raise you are going to run about 25 passes of memtest (Test #5 only for now) Once you get errors there are a few things you can do here:

1- Lower the HTT\FSB until its stable.
2- Raise the Vdimm (RAM Voltage) to see if that makes it stable, but remember some RAM doesn’t like a lot of vdimm and it could damage them.
3- Loosen the timings to make it more stable.

Which option you choose is pretty much up to you and how much you know about overclocking RAM. I can’t stress it enough to read all you can about overclocking because there is so much info out on the net between guides and forums alone.

Now once you decide what option you are taking, continue testing with memtest #5 until you’re at your max for the ram without errors. Then I would suggest running all the tests in memtest overnight - 8-10 hours.

If it passes the long test then you want to leave those settings like they are and boot into windows. It might not be stable in windows even if it passes memtest though. I’ve noticed with a64’s that I could pass hours of memtest sometimes but have instability in windows. If you aren’t stable then you need to either give more vdimm, loosen the timings or back off the HTT\FSB some.

If you do make it into windows I would run 32m SuperPi, 30min OCCT, 3dMarks and then Prime95 overnight, just like we did to finalize the CPU’s max. If it fails any of these you have a few options…

1- Lower the HTT\FSB until its stable.
2- Raise the Vdimm ( Ram Voltage ) to see if that makes it stable.. But remember some ram doesn’t like a lot of vdimm and it could damage them.
3- Loosen the timings to make it more stable.
4- Settle with what you have so far.

If you decide to go with one of the options from 1-3 then keep repeating the tests until you are happy and stable.

CONGRATULATIONS !!
You just found the max MHz of your ram..


Now that you found the max of your CPU and ram it should be a little easier to clock it together..

Lets say your CPU maxed out at 2800mhz with its default multi of 12x.. But your ram maxes out at 250mhz..

12x 250 = 3000mhz.. That won’t work ..lol..

11x 250 = 2750mhz .. That will work but your cheating yourself 50mhz of CPU power.

12x 233 = 2796MHz .. That will work and get you closer to the max of your CPU. And running the ram little slower then the max you found before to achieve the higher CPU MHz might also allow you to tighten up the ram timings a little.

Now there is always the option to use a divider for your ram which will get you closer to your CPU and RAM’s max....

10(CPU multi) x 278(HTT) = 2780mhz (CPU speed)

If you use a 9\10 divider with this config…

278 \ 10 x 9 = 250mhz (mem speed)

Whatever you decide there really isn’t a right or wrong way to do it. The only way to find out which way is best for you to run is test test test!! Run benchies with different configs and see which performs the best.

[planetgong]

Thanks. I have read something similar to that before. Well I left Prime on overnight and it is completely stable at 2.8GHz. But if I up it even to 282 it becomes unstable. Strange!! Never mind, I can't really complain at it running at 2.8!!

[Hullz-Modz]

Interesting read, helps alot.