I7 uncore/dram rule

[Acebmxer]

I know for the i7-920-975 cpus uncore must be 2x memory mutli and the 980x and the 970 only need 1.5x memory multi.

My question is why? what happens if you run lower then 2 x memory multi (920-975) or less then 1.5 x memory multi (970-980x).

If you have a link to a site that can explain this please post it here.

[Lsdmeasap]

Re: I7 uncore/dram rule

Lower than will not boot, it's that easy :)

Although I have not tried it with massive voltages or anything, so it might, but I doubt it as I have tried with normal or reasonable voltages.

[Acebmxer]

Re: I7 uncore/dram rule

you are correct once again :)

I thought i was able to with my 930 before i knew but I must have been mistaken b/c i just tried and it would not boot at 15x uncore 8x memory. but will at 18x uncore 8x memory. both at 215 blck.

[Lsdmeasap]

Re: I7 uncore/dram rule

Ya, I've tried it at 133Bclk with low multi's and it doesn't work at all.

It might if you super over-volt things, but I doubt it.

[wibujo]

Re: I7 uncore/dram rule

I have the 980x and before I knew about the 1.5 X System Memory Multi rule I was running it at x17 uncore/Mem Multi @10. I scored my highest Memory score and Lowest latency but was not stable. Memory Score:14.64GB/sec - Latency 46.6ns. (24GB's@2000) My question is: What damage am I doing to my MOBO, CPU, or RAM ???

[Lsdmeasap]

Re: I7 uncore/dram rule

That is fine, it wont hurt anything.

Anyway at x10 memory multi your min. would be x15 and then 20+ would be max, so you are in the middle anyhow so you are fine.

I use x22 uncore most of the time when using x10 memory multi on 980X.

24GB @ 2000 is great!! What timings did you have set, and this is the memory in your sig?

[Acebmxer]

Re: I7 uncore/dram rule

So there is a upper limit also or just how crazzy you feel adding qpi/vtt voltage?

[shadow6491]

Re: I7 uncore/dram rule

This is where I have found the limit of my overclocking to come from.

The CPU Uncore Frequency can not run at 4000mHz so I can not run my memory which is rated at 2000Mhz at 2000Mhz.

My cpu I have tested up to 4.2Ghz but in the end I am only running it at 3.87 using a BLK of 155.

I am also confused as I read that a lot of people recommend setting the Uncore clock ratio to that of the CPU ratio +1. How can you achieve clock speeds of greater than 4 ghz if Uncore is maxed out at 3950Mhz.

If anyone has any other suggestions of combination's to get better performance out of my setup please advise.

[Acebmxer]

Re: I7 uncore/dram rule

what cpu are you using? If your ruinning a 920-975 i7 then thats about average . my 930 has a weak imc and needs some volts. My 920 and run 2000 ram at 200 blck and decent voltage but not suitable for 24/7 imho. I havent read any where about uncore ratio to cpu ratio. I heard people saying they have to keep their uncore faster then their qpi speed. I dont have that problem.

[shadow6491]

Re: I7 uncore/dram rule

I made up this table in excel to try and compare the different blk freq with that of Uncore and memory freq and the resulting CPU speed.

I tried to post the table here but got message to long.
I found some very interesting results that I just could not explain for example a blk of 155 memory multiplier of 12 a uncore multipler of 25 and cpu at 25 should be the same as
a blk of 186 a memory multiplier of 10 an uncore of 20 and a cpu of 21 or 22 but it doesnt

But then when I go back and test my previous stable settings I get bluw screns of death as well. I can see why some people would like a little help in this area.

Some of the answers are a real cop out. actually those are more over in the corsair forum.

[Lsdmeasap]

Re: I7 uncore/dram rule

There is no upper limit rule, only what your CPU can handle.

Most CPU's can do 4Ghz uncore once you give it enough QPI/Vtt, some better 4.2Ghz, and some of the best can do 4.4-4.5Ghz. That's under normal cooling, once you freeze the chip then it can do quite a bit more usually.