overclocking.... again

Speedfan really is the best tool I know of for this, but you can use Coretemp. I just like Speedfan because it shows me VDroop.

1. I haven't seenan app that displays this.

2. One must be showing your setting and the other is reporting the actual current voltage level.

Other than making me jealous of all you GO stepping owners once again, yes all of the screenshot info looks good

CoreTemp only reports the CPU VID. This magical number will determine how well your CPU overclocks. The lower, the better. We have the same VID rating, and according to other reports, our CPUs [VIDs] are pretty crappy overclockers.

Here's what I forced out of mine though:



As you can see, it requires jacking the juice UP.
Lower VID ratings could acheive the same clock at much much less voltage.

PLEASE DO NOT ATTEMPT THAT MUCH VOLTAGE ON YOUR SYSTEM.

Especially on AIR [cooled], you're simply not going to get it.
Checkout these LOAD temps. I'm on water.



Room temp is about 70F. Water pundits will argue that those temps are too HOT for a water system. And I would probably agree. But I can't fit a triple radiator in my case, nor have 100CFM+ fans spinning over them, thats way too loud.

I've ran PRIME for 3 hours straight at those temps, system didnt seem to mind at all. Thats enough for me to award it stability points. Now lets see how that changes when summertime weather hits.

Edited by Duke - 04 Apr 2008 at 4:26am

Darn it Duke, I completely forgot about VID. Must be past my bedtime.

and seriously, in case anyone missed this before, I have to do this:

PLEASE DO NOT ATTEMPT THAT MUCH VOLTAGE ON YOUR SYSTEM.

I'd be terrified to run my CPU at those voltages, let alone temps.

Mythius, the VID is a value the motherboard detects from the CPU and is used in setting Vcore. The lower this number, the less voltage the CPU requires. Lower voltage levels to achieve a given speed mean less heat, so a lower VID should mean more overclocking headroom, at least in theory.


Edited by Tyler Lowe - 04 Apr 2008 at 3:25am

Not exactly.

Really what you're looking at with RAM is a range of possibilities. Well, I suppose that's true of every system clock you can tweak. Let me see if I can make this less murky.

Disclaimer: I am going to try and explain parts of one approach to overclocking. I am not advancing one method over another, and I am still learning myself.

Let's say you are trying to overclock your CPU. No matter whether or not you select "linked" or "unlinked", rest assured that the RAM and FSB are linked one way or another. When you go "unlinked" you're relying on dividers that can produce all manner of funky clocks. I'm still learning about how those work, and reading about it makes my head hurt a little, so don't ask for an explanation of that please. The main thing is, I have found that you gain greater stability while working with "linked" settings which force set ratios on the memory and FSB. This is true at least on my 680i motherboard, and many other 680i owners have reported similar experience.

So back to the RAM. I said it was really a range of possibilities. The low end of the possibilities you'd be considering is a RAM speed half that of the FSB QDR. So, if you wanted to overclock your Q6600 to 3.6 GHz, you'd need a FSB speed of 1600MHz, assuming a 9x multiplier of the CPU.

CPU: 9x 400MHz= 3600 MHz
CPU FSB: 4x 400MHz= 1600 Mhz (Quad Data Rate or "effective speed")
RAM: 2x 400MHz= 800 MHz (Double Data Rate or "effective speed")

See a pattern there?

So the *minimum* desirable RAM speed would be 800MHz. You would actually like it to be slightly faster than this to combat latency, or the time the CPU's cache needs to wait for a response from the system RAM. This is a very straightforward example. It gets more complicated, but I will stick with 3.6GHz for the moment.

I don't know what the ratio selections on the 780i are, but for my board, they are:
1:1
5:4
4:3 (auto)
3:2
Sync Mode (2:1)

Back to my RAM. I know the FSB speed is going to be 1600. Sync mode would leave my RAM running at 800MHz. (1600/2 * 1 = 800). If I wanted to run 3:2, I would need 1066MHz RAM (1600/3 * 2= 1066.667). If I wanted to run at 4:3, I am now at the limits of DDR2, around 1200MHz (1600/4 * 3). These are all *possible* speed selections. I know I want to run faster than 800MHz, and the next available setting is 1066MHz if I intend on using one of the available ratios in linked mode. Foprtunately, for the purposes of this example anyway, my RAM is rated for 1066! Yay! Pretty simple example.

Now, what if I wanted to overclock, but only to 3.4 GHz? My RAM is rated to 1066, but now, 3400/9= ~378.  378*4= 1512.

Looking at the same ratios, Sync mode would leave you at 756Mhz. 3:2 would give you 1008, and 4:3 would be 1134. If you are looking between a choice of 1008MHz with decent timings, or 1134MHz with not so decent RAM timings, you may find it is advantageous to downclock the RAM.

This is one example of when, and why you would lower RAM speed.

Yes, that is exactly correct.

That's one way to look at it, yes. I see it as "striking a balance" as much as anything, but my RAM doesn't have the sort of headroom yours does for faster clocks, so I am forced into compromises you may be able to avoid.

I was *so* close to a sweet OC at 3.2GHz running my RAM linked up at 960MHz, but I just could not get it to go at the timings I wanted. Real shame too, I thought I was on to a nice payoff for the 20 hours I had put into tweaking. That sort of thing is inevitable if you want to explore overclocking though.

One thing I will toss out as a warning:
Overclocking can be extremely addictive. Especially if you like to tune mechanical and electronic systems.

Keep some limitations in mind before you start. Things like "no matter what, I will not exceed 1.5V to my CPU core" or "no matter what, I will not push past the RAM manufacturer's recommended  voltage levels".

It may sound silly, but when you start hitting a limit, you can be tempted to do dumb things in the heat of the moment. (oh, how I have been tempted ). Having a set of rules in mind ahead of time has kept me out of trouble, so I pass that along as a suggestion.