DDR3 RAM

[Peter Tsang]

Hi folks,

Considering building a new system. I'm familiar with case, motherboard, CPU, PSU..etc except just memory, never quite into it.

So I'm checking out one of these http://www.corsair.com/memory/xms-classic/xms3-ddr3-memory/cmx4gx3m1a1333c9.html

When it says PC3-10600 (1333MHz) in Speed rating, what exactly does the number 10600 tell me? Also is 1333MHz is the maximum speed that it can out up with?

Thanks!

 

[Peter Tsang]

The rated speed is the fastest it is stable to. You can buy faster ram and make it go slower. If you are overclocking, it makes sense to get faster ram as when you overclock the CPU you also overclock the ram (this can be changed, if you like so it is unlinked to the processor sped)

Thanks! I know better now!!

 

[Peter Tsang]

I need a confirmation.

Say if I have to choose from 1333 or 1600, I will choose 1600 only if I want to overclock the CPU later. If not, then I will choose 1333 becoz 1333 is obviously cheaper than 1600.

Do I get the concept right?

 

[Peter Tsang]

It depends what type of system you're building.

If you build a Sandy Bridge system and use a processor with an unlocked multiplier (2500K or 2600K) then memory speed is irrelevant to overclocking.

If you build a system using a processor with a locked multiplier, where overclocking involves increasing the Base Clock, then higher speed RAM may allow you to overclock further.

You can't really overclock the locked multiplier Sandy Bridge CPU's using the Base Clock method as too many other things are affected by this.

I don't know what it's like in Hong Kong but in the UK 1600MHz DDR3 is virtually the same price as 1333MHz DDR3 so there's little point in buying 1333MHz.

Edit

If you're building a new system today then Sandy Bridge is really the only way to go unless you're on a very tight budget.

Okay, let me get this right.
So you're saying that with the unlocked multiplier, the only concern is the 2500K/2600K's temperature? As long as it is within the limit, I can overclock as highest as it can afford?

In Hong Kong, I will have to check.
By the way, what is the highest DDR3 RAM speed ?

 

[Peter Tsang]

Temperature and voltage, but they go pretty much hand in hand.

It's generally recommended that the maximum voltage for Sandy Bridge is 1.38-1.4V depending on who you listen to.

Most of the "K" chips will overclock to 4.5GHz and some a lot more.

DDR3 is generally available up to 2133MHz but the sweet spot for price/performance is 1600MHz (at least at UK prices).

4GB of 1600MHz DDR3 is around £25-£30 and 8GB of 1600MHz £50-£60.

1866MHz or 2133MHz costs quite a lot more.

Have a read of this:

The Best Memory for Sandy Bridge

Memory above 1600MHz doesn't offer a lot of benefit compared to the cost.

Thanks Surveyor, you have provided me with the information which is the most sought after.

So if it goes over 1.4v then the Sandy Bridge will be damaged, do I get it right?

The "K" chip is very overclockable then. Stupid question again: 2500K starts at 3.3GHz, so let's say it's o/c to 3.6GHz, is it faster than [email protected] then?

I know DDR3 starts at 1333MHz, then 1600MHz, now I know 1866MHz and 2133MHz also. So let's say what multipliers are available from an Asus iCore motherboard? And what about Gigabyte's?

 

[Peter Tsang]

Additional informaton:

If this is a gaming rig then a 2500K is what you need. There's basically no difference between a 2500K and the more expensive 2600K in gaming.

The main difference with the 2600K is hyperthreading which may be of use for stuff like video encoding.

To overclock a 2500K or 2600K you need a P67 or Z68 motherboard.

The additional features of the Z68 chipset are explained here.

Not all Z68 motherboards implement all the additional features. Notably some Gigabyte boards.

Great Great to know specially the 2500K and 2600K. The additional cost would better be put into a SSD which is a wish to me, or practically a 24" LCD monitor becoz I want to see 1920X1200 resolution.

You mentioned hyperthreading, I have this question in mind for some time now. You know TMonitor? http://www.cpuid.com/softwares/tmonitor.html

I played around with it on the other day while I was o/c'g the Q6600. In the log, I noticed the behaviour of the various cores of the CPU. The stock speed is 2.4GHz and the CPU was now @ 3.6GHz. But not all four cores were running at 3.6GHz. The first column is core 0, second column core 1, third column core 2, fourth column core 3. It reads something like the following:

3.6 2.4 2.4 2.4
3.6 2.4 2.4 2.4
3.6 2.4 2.4 2.4
3.6 2.4 2.4 2.4
3.6 2.4 2.4 2.4
.... .... .... ....
.... .... .... ....
.... .... .... ....
2.4 3.6 2.4 2.4
2.4 3.6 2.4 2.4
2.4 3.6 2.4 2.4
2.4 3.6 2.4 2.4
2.4 3.6 2.4 2.4
.... .... .... ....
.... .... .... ....
.... .... .... ....
2.4 2.4 3.6 2.4
2.4 2.4 3.6 2.4
2.4 2.4 3.6 2.4
2.4 2.4 3.6 2.4
2.4 2.4 3.6 2.4
.... .... .... ....
.... .... .... ....
.... .... .... ....
2.4 2.4 2.4 3.6
2.4 2.4 2.4 3.6
2.4 2.4 2.4 3.6
2.4 2.4 2.4 3.6
2.4 2.4 2.4 3.6

Now, how do I interpret that? Is performance of the Q6600 @ 3.6 is not at full throttle?

 

[Peter Tsang]

No one really knows about the voltage but 1.38-1.4V seems to be the general consensus of what's safe.

Clock for clock a 2500K is better than a Q6600. So a 3.6GHz 2500K will perform better than a 3.6GHz Q6600.

Memory multipliers are irrelevant when overclocking the 2500K.

You don't change the base clock only the CPU multiplier. So at stock a 2500K runs at 3.3GHz (multiplier of 33) and you can set the RAM to run at 1333MHz, 1600MHz or whatever.

To overclock to 4.5GHz you increase the multiplier to 45. This does nothing to change the RAM which will continue to run at 1333MHz, 1600MHz or whatever.

Oh, you learn something new every day don't you!

So it's totally different from what we are doing for overclocking a Q6600...

Is that one of a properties of the iCore generation?

So there won't be a stability concern because of the RAM speed not catching up with the FSB/CPU speed so on and so forth...is that so?

 

[Peter Tsang]

It's a property of any processor with an unlocked multiplier.

AMD have Black Edition processors which work the same way.




That's correct because you don't change the FSB (Base Clock for Sandy Bridge) to overclock.

My thinking process about this aspect of CPU technology is pegged with locked multiplier Q6600 for example so it takes time for me to imagine what it is like for an unlocked multiplier.

 

[Peter Tsang]

Surveyor,

I'm running Prime95 with the CPU @ 2.4 stock speed. This is what I get from the temperature monitor




How come they are not eveny loaded?

 

[Peter Tsang]

Just remember that only the 2500K and 2600K have unlocked multipliers.

The plain 2500 and 2600, and all the rest of the Sandy Bridge processors, are not very overclockable as it's not recommended to change the Base Clock.

You can do some tweaking with Turbo Boost multipliers but overclocking is much easier, and higher, with the "K" series processors.

I see! That's why they are more expensive than other 2500s. If I wait for a month or two, do you think they will still be available?

 

[Peter Tsang]

Try Real Temp or Core Temp.

They seem to give a more reliable reading.

Load temperatures between 45 & 58 degrees on the core are OK but the big difference suggests your cooler may not be seated correctly.

There's usually some difference between cores but 13 degrees is a lot.

So what actions should I take, I just put the new H60 in. It's quite painful to do it again...

 

[Peter Tsang]

Surveyor
I ran the test, horrific!
Now @ 3.6GHz, both core1 and 2 reported 82C
I stopped immediately.
This is now thei dle temperature

I'll go tighten the screws now....

 

[Peter Tsang]

Surveyor,

I tightened all 4 screws now, but the result is the same:

 

[Peter Tsang]

You probably need to do a bit more than just tightening the screws then.

It looks like you'll have to remove the cooler block from the CPU, re-apply the thermal paste and then re-fit it very carefully.

This problem exists before the H60, I was using the Silent Knight. Core1>Core2>core3>core4

Just now I have ran Prime95 again. Core 1 reached 98C where as Core 4 was 68C ridiculous!! A difference of 30 degrees.

I am tired I need to get up at 7am. I guess I will have to do it tomorrow after work.

But if I reapply thremal grease I will lose the original grase from Corsair, I heard the default grease is very good grease.

I have Thermaltake TG-1 standing by, is it a good brand?

 

[Peter Tsang]

On second thought Surveyor,
Could that be the grease covering Core 1 and Core 2 are too thick making hard to conduct heat? Where as Core 3 and Core 4 are just about right thickness?

There is a map about the orientation of all 4 cores...do yo have the link?

 

[Peter Tsang]

Just a quick search gave me this
http://www.xtremesystems.org/forums...roper-Quadcore-water-block-mounting-technique

Surveyor,

Something I am not sure. Is that the thicker the grease on a core, the hotter it will get?

Is there a hard and fast rule for distributing grease over the CPU ? Also If I am going to repaint, should I put the grease on the CPU of on the heat sink?

 

[Peter Tsang]

Surveyor

I opened up the sink and found core 3 and 4 are not covered at all!!!!!! That's the default thermal paste on the H60

I reapplied the paste, it's thermaltake.

They are now closer in temperature.

But temperature seems to be higher or they seem alright to you...check for me I am tired....
Thanks!!!

 

[Peter Tsang]

Prime95 in progress Test 2...here is the temp:



Core 1 and Core 2 are cooler than before, they were 98C before reapplying the paste.

What you reckon?

 

[Peter Tsang]

If that's still at 3.6GHz then the temperatures are OK(ish) but you don't want to be any higher and a few degrees lower would be better.

Ideally Cores #0 and #1 should nearer to the temperatures of Cores #2 and #3.

It looks like your cooler and CPU just don't want to sit entirely happily with each other.

A new day has begun, good morning Surveyor.

You mean the overclocked temperature is okay? That's touching onto 80C.....

Guess what happened before the rework of the cooler: I opened it, half of the CPU surface (assuming core 1 & core 2 area from your picture) was covered by the default paste, HOWEVER, you might not believe this, the other half (i.e. core 3 & core 4) was not! The default paste was on the cooler's copper surface instead. Having said that, as we can read from the HWMonitor, the temperatures of both core 3 and core 4 are lower than core 1 and core 2.

After the rework, now that core 4 is still the lowest. What I did was I made the paste from core 1 through to core 4 in a line, stirred around until almost the entire CPU surface is covered by the paste.

This morning, I fired up the machine again. Core 1 and Core 2 were both at 46C and core 4 was 39C.

You know what I wish? I wish to bring core 1 through 3 down to 39C. If core 4 can stand at 39C at idle state, why not the other three, it's the same paste afterall! What have I done wrongly?

 

[Peter Tsang]

Good night, see you later. Many thanks!!!