DDR3 - Why is it so dishonest?

[McstylisT]

So at the risk of ULTIMATE FAIL , when I plug my 1600MHz 7-7-7-24 DDR3 memory into my Gigabyte P55M-UD2 motherboard, running at standard 133 BCLK, what will the default timings be at 1333MHz?

Its hard to say the timings it will auto run at. ? Depends on the ram itself.

For one , the memory is probably running at 1.5v standard on most systems. This is obviously not enough to sustain a 1600mhz speed. So with that in mind it will run fine at standard 1333mhz. Which is what Intel's official max speed ram should officially run at. Anything over this is an overclock , regardless of what the modules say or state. Lets remember the new CPU's from Intel have integrated mem controllers now so its much more sensitive to this type things.

Raising your voltage on the ram to 1.65 could effectively run the ram 1600mhz auto. ? It might not but thats how it could work. etc.

Your basically buying 1333 ram , individually tested at 1600mhz with higher 1.65v. Like premium modules. To run at these speed ( reason why its called "Xtreme memory profiles " ) you need to adjust your system settings to allow the overclocked settings to take place.

McT

 

[nheather]

So at the risk of ULTIMATE FAIL , when I plug my 1600MHz 7-7-7-24 DDR3 memory into my Gigabyte P55M-UD2 motherboard, running at standard 133 BCLK, what will the default timings be at 1333MHz?

Based on the memory I have just used, I suspect that it will default to 9-9-9-24 @ 1333. But since you have a P55 you should be able to enable XMP and then it should automatically pick up 7-7-7-24 @ 1600. It should run fine at that because I was informed by the manufacturer that it was specifically designed for P55.

Cheers,

Nigel

 

[kidscruff]

Aye, but that bumps my CPU base clock form 133 to 160 - something which I don't want to happen (yet).

 

[nheather]

Aye, but that bumps my CPU base clock form 133 to 160 - something which I don't want to happen (yet)

Okay, I assumed that it uses a memory clock ratio like my board, so that the CPU speed is left unchanged.

Cheers,

Nigel

 

[kidscruff]

Well it seems the i5 CPU (in an attempt to stem overclocking?) removed some of the memory clock multipliers - so maximum is x10. That's why at default CPU base clock (133), the "fastest" memory is 1333MHz.

The P55 motherboard obviously supports much faster memory, but for i5 if you run memory at 1600 using the XMP, it has to bump the CPU base clock to 160 in order to to reach that (160x10). This doesn't seem to cause a huge problem though, as the CPU multiplier can be decreased to give you approximately the same speed. But it is effectively an overclock (i.e. 133x20=2.66GHz to 160x16=2.56GHz)

From the German G.Skill 1600C7 review (here):

The XMP profile just works, so long as you want to run the i5 at 160. I wanted to run my i5 at a default 133, so would have to run the memory at 1333. But you can see from the JEDEC timings above that this would default to 9-9-9-24/25.

I could program the faster timings myself and quit complaining, but I'm a lot happier if it just plugs in and runs great without me messing around!

In the end I've changed my order for the DDR3 OCZ Platimum low voltage 7-7-7-20 4GB kit, as this has these timings programmed directly to the SPD. There's no XMP profile, but I'll be happy with everything chugging nicely at default settings.

It may seem obvious to some, but for the laymen around here, it seems ridiculous that you get amazing timings using the XMP profile, but if you can't use the XMP (or run at a different frequency), the "standard" timings are rubbish! Why didn't they program awesome timings for all their frequencies, like the SPD of old?

 

[kevpuk]

Pretty sure that the ASUS P7P55D Deluxe has some magical 12x memory bootstrap.....I have this board and will take a look Sure I read in a review or similar that ASUS has weaved some magic around native 1600MHz ram speed via this method....
TBH, i just enabled XMP to test my (unfortunately 1 defunct module) G.Skill Ripjaw cl7 stuff...quick fix, but will take a look for this bootstrap when the Patriot replacement stuff arrives later

 

[faugusztin]

And i'm pretty sure it don't have anything like that. Memory controller and memory multipliers are inside the CPU, so the boards can't change the hardcoded maximum multipler in Core i5 from x10 to anything else. My Gigabyte P55-UD5 pushed the base clock to 160 like other said.