Quick overclock question for those in the know

[vwgolfman]

Thanks for your info.
I am getting some results now.

I set the RAM timings manually as you suggested.

My CPU VID is 1.3V by the way.
I have disabled C1E and EIST but they didn't seem to affect the CPU VID anyway (monitored in CoreTemp). I was under the impression that with C1E and EIST enabled that the CPU VID would change when under load (Prime95) compared to idle but it didn't. Why is this?

Currently these are my settings....
Clock 320
Multiplier X9
CPU Clock is currently 2.885GHz
DRAM 1:1.25 (800MHz)

Core temps under load (Small FFTs) are 57, 48, 48, 57.

It appears to be perfectly stable.

I intend to up the External Clock to 333 next and leave the RAM divider as it is (that will give 833MHz RAM).
Let's see what happens (will report straight back)......

What should I do next if it is happy at 333?

PS all voltages are still at stock.

EDIT: BSOD just before reaching Windows!

Should I up the CPU VID one notch or more? One notch takes me to 1.3125V. I did this but still had a BSOD so I have taken it up 2 notches to 1.325V and now it boots.

 

[Teaf]

Little confused by your post, are you at 333x9 with 1.325v vcore? If so that is fine, and if it looks stable then I would Prime95 it for 8 hours or more to ensure stability. After that, depending on you core temperatures under load, you can either go higher on the CPU if you wanted too, or just bring the RAM more up to stock speeds.

 

[vwgolfman]

Sorry for the confusion.

I am at 333x9 with a 1.325V VCore.
However, although Prime95 ran OK when I ran 3dMark06 the first test bombed out.

I suspected RAM as this is now running at 833 at 1.8V.

For this reason I have taken the RAM back a notch on the divider and I am about to run 3dMark06 again.

On the Corsair website there is a .pdf for the RAM I have and it states:

SPD 5-5-5-18 @ 800MHz
5-5-5-15 @ 1066MHz 2.1V

Does this mean that SPD will not control timings above 800MHz?
i.e. I MUST set timings manually for >800MHz?

Do these figures also suggest that in order to go >800MHz I MUST increase DDR2 Voltage?

 

[Teaf]

Does this mean that SPD will not control timings above 800MHz?
i.e. I MUST set timings manually for >800MHz?

Do these figures also suggest that in order to go >800MHz I MUST increase DDR2 Voltage?

SPD just gives set values for various stages of Mhz's / timings for you to use, you can use values in the middle of those set by the SPD without any problems at all you just have to adjust any timings and voltages accordingly. Most of that just comes with knowledge, such as adding 100 mhz would probably need a voltage increase for your RAM to about 1.9 / 2.0v but you're only 33 Mhz over the SPD rated 1.8v so I doubt it would need a voltage increase.

I would try setting the RAM back to default, ie. change the FSB : DRAM divider so that your RAM gets close to stock. You can leave the timings as they are currently set as that's what they should be, but you will need to change the voltage from 1.8v to 2.1v. Try that and see if 3dMark still bombs out, and if it does try adding another very small amount of voltage to the CPU and see if that helps.

I'm thinking it is going to be one or the other, either your RAM is being picky or the CPU just needs a little bit more voltage.

 

[vwgolfman]

Complete update:

Now at 333 x 9 (3GHz) with NO increase in CPU Core (it is on 1.3V stock).
DDR2 divider at 1:1.2 (800MHz). Manually set timings as you suggested 5-5-5-18.
All other voltages etc are at stock.

All is stable with core temps of 59,49,49,59 under load (Prime95 small FFTs).

1) I cannot afford to have my machine crash on me. For this reason would you recommend upping the CPU Core from stock anyway (am I right in thinking I have some headroom with those core temps)?
If so then to what voltage?
Is there any advantage to running the CPU on the edge in my situation (i.e. JUST giving it enough Volts) or would I be better off giving it some headroom?

2) Is it imperative that C1E and EIST are disabled?
What will happen if I enable them?

3) There is a setting in the BIOS to enable the CPU fan speed to be controlled by (it's temp?). Am I OK to leave this enabled or should I disable this?

4) Should I run all load tests on the CPU before worrying about RAM?

5) Once I am happy with the CPU and want to attack the RAM can I use it "by SPD" or should I set the timings manually?
If manually then should I set them as per the .pdf (5-5-5-15 and 2.1V)?

or...should I increase RAM speed and voltage slowly and check results as I go with Prime95's "Blend"?
Will it be necessary to use Memtest86?

I think that's all of my questions for now. Thank you flibby.

 

[Teaf]

Complete update:

Now at 333 x 9 (3GHz) with NO increase in CPU Core (it is on 1.3V stock).
DDR2 divider at 1:1.2 (800MHz). Manually set timings as you suggested 5-5-5-18.
All other voltages etc are at stock.

All is stable with core temps of 59,49,49,59 under load (Prime95 small FFTs).

Excellent!

1) I cannot afford to have my machine crash on me. For this reason would you recommend upping the CPU Core from stock anyway (am I right in thinking I have some headroom with those core temps)?

You could just run Prime95 for 24 hours. This will guarantee stability on the machine. 8 hours is normally the target, but I've seen peoples overclocks crash and burn after about 14 hours. So maybe start it and just let it run for a day when you have all the settings correct that you want, then see if it's OK after 24 hours, if so you are golden.

Is there any advantage to running the CPU on the edge in my situation (i.e. JUST giving it enough Volts) or would I be better off giving it some headroom?

Just enough volts is fine if it's completly stable under Prime95 for 24 hours. But you can give headroom if you feel more comfortable doing that, either way is fine but it's more a case of whether you'd be worrying with it being at stock volts. If you wanted to give it headroom then just move from about 1.3v to 1.325 and that should be sufficient, you'll get a small increase in temperatures though.

2) Is it imperative that C1E and EIST are disabled?
What will happen if I enable them?

You can definetly have it enabled, this case of turning it off was to identify the actual VID from Core Temp, as if you leave it on it sometimes shows a varying VID in Core Temp. All that it will do when you enable it is drop the multiplier and the voltage of the CPU when it's idle - I very very much doubt that it will cause instabilites with your overclock as it's just a mild one. People that overclock heavily do turn it off permenantly as it can cause instability due to constantly changing vcores.

I would enable it.

3) There is a setting in the BIOS to enable the CPU fan speed to be controlled by (it's temp?). Am I OK to leave this enabled or should I disable this?

Enabled if your temps are okay, and judging from what you said your load temps are I would just leave it on. It'll be far quieter for you, as disabling it with make the fan work at full blast (assuming you haven't got the Zalman Fan Mate attached, otherwise it won't actually do anything since the speed of the fan is controlled by the Fan Mate).

4) Should I run all load tests on the CPU before worrying about RAM?

Yes, I would worry more about the CPU than the RAM since your CPU is overclocked the RAM is not. As mentioned, I would complete the 24 hour cycle of Prime95 using Small FFTs and if you really wanted to feel comfortable about stability you could run a Blend test for 8 hours which will test the RAM.

5) Once I am happy with the CPU and want to attack the RAM can I use it "by SPD" or should I set the timings manually?
If manually then should I set them as per the .pdf (5-5-5-12 and 2.1V)?

or...should I increase RAM speed and voltage slowly and check results as I go with Prime95's "Blend"?
Will it be necessary to use Memtest86?

Set them manually, otherwise they probably won't start with what they should be at due to standarisation of DDR2 and motherboards booting from 1.8v stock. Just enter the details accordingly into the Advanced BIOS Settings, and change the DDR2 voltage to 2.1v and FSB : DRAM ratio to get it as close to stock as possible.

I would run an 8 hour Blend test after you have put the RAM back to stock, it just clears you concience that it's all okay and won't crash. You shouldn't need to run memtest86 if you run a Blend for 8 hours, although you can if you want to just to check for any errors but if it passes a Blend I personally wouldn't bother.

 

[vwgolfman]

Thanks again.

I shall be running my long Prime95 test overnight and through tomorrow.

I have just attempted to up my RAM but it doesn't like it.

By default the divider is 1:1.5 and with a default clock of 272MHz this gives a RAM speed of 816MHz.

Now with my clocked machine I set the timings to 5-5-5-12 and upped the Voltage to 2.1V
The RAM won't even run at 833MHz (1:1.25) but it will at 799MHz (1:1.2).

Any ideas?