Memory speed & the i7

[BTRY B 529th FA BN]

I'm in the middle of sorting out my options. I have come to some good ideas on how to save money on my new i7 rig but am curious how the memory speeds relate to clocking the i7. I use to run an AMD machine about 3yrs ago and it was simple. DDR 400 would max bus speed at 200 without having to overclock my ram. I'd like to overclock my i7 920 to around 3.8-4.2Ghz. I currently have 2x2 DDR3 1600 sticks and have another 1x2gb on the way for a triple chan config. Will I be limited by my ram in reaching 3.8-4.2Ghz?

 

[Sentry2]

Depends on your sticks bud. What 4GB kit do you have and what motherboard are you gonna be running? 1600MHz will get you 200blck with out overclocking your ram.

On that 920 200blck x 20(stock multi with turbo off) will net you 4GHz. 3.8GHz should be cake. I would shoot for 3.9 - 4.0GHz....more if you're feeling brave and your cooling is up to the task.

 

[BTRY B 529th FA BN]

Originally posted by: Sentry2
Depends on your sticks bud. What 4GB kit do you have and what motherboard are you gonna be running? 1600MHz will get you 200blck with out overclocking your ram.

On that 920 200blck x 20(stock multi with turbo off) will net you 4GHz. 3.8GHz should be cake. I would shoot for 3.9 - 4.0GHz....more if you're feeling brave and your cooling is up to the task.

I have these these. and 1 more 2gb stick of the exact same on the way.

Not sure of the mobo. I've always stuck with Asus but I'm sorta tempted by the Biostar for its layout. I'll be using one GPU and I need 2 PCI slots. I already have the Thermalright Ultra 120 eXtreme but if it comes to it, I'll swap out my Q9650 in my H20 box for the 1366 setup.

EDIT: or the EVGA

 

[taltamir]

save money on an i7? there are so many worthwhile upgrades and uses for money i would put before buying an i7... not to mention we are going to have the dual chanel version in a few months...

Are you using a velociraptor or a quality SSD? are you using 8GB of high speed DDR2 ram? very good overclocker mobo based on X48 or P45? a fast 45nm C2Q?
If the answer is yes to all the of above, than you should upgrade to an i7, but if that was the case saving money wouldn't be an issue.

Also, if that was the case than the i7 920 would not be an upgrade. The 920 is simply not cost effective (unless you intend to do zero over clocking, even than it is iffy...), there are plenty of cheaper and faster systems you could build from older intel CPUs. Only the 940 and 960 are worthwhile, but those REALLY cost too much.

 

[Sentry2]

Those should work good I would think.

I had some serious issues with some of the pre-i7 OCZ DDR3 sticks that needed 1.8v or better. It could have been the board though as well. The newer low-voltage stuff works like a charm though.


The EVGA X58 is a great board (and the slot layout is the best of the bunch for me)...and while it might not be the best board (everyone has a different opinion) their customer service sure as hell IS the best.

I know what you mean though about always sticking with ASUS. My X48 Rampage Formula was the BEST board I've ever owned. That thing would chug along all day @ 475FSB (1900MHz) with a G0 Q6600 and a X3360 and never complain. Eh, the Q6600 I ran @ 8x475 (3.8GHz). I was playing a game the other day and some guy tried to tell me he had a Q6600 @ 4.5GHz on water.... :laugh:

 

[Sentry2]

Originally posted by: taltamir
save money on an i7? there are so many worthwhile upgrades and uses for money i would put before buying an i7... not to mention we are going to have the dual chanel version in a few months...

Are you using a velociraptor or a quality SSD? are you using 8GB of high speed DDR2 ram? very good overclocker mobo based on X48 or P45? a fast 45nm C2Q?
If the answer is yes to all the of above, than you should upgrade to an i7, but if that was the case saving money wouldn't be an issue.

Also, if that was the case than the i7 920 would not be an upgrade. The 920 is simply not cost effective (unless you intend to do zero over clocking, even than it is iffy...), there are plenty of cheaper and faster systems you could build from older intel CPUs. Only the 940 and 960 are worthwhile, but those REALLY cost too much.

The 920 is perfectly fine for overclocking...what are you trying to say about the 920's oc potential? The 940 is probably not worth double the cost for an extra 200MHz on the overclock( assuming it will even net you that when you pass 4GHz ) and the 965 as far as I'm concerned is a huge waste unless you're running phase.

Nobody said anything about saving money er by sticking with last gen...I think you have the wrong thread....?

The i7 920 is a great chip and the X58 is the superior Multi-gpu platform if he ever decides to go that route. DDR3 prices are also not as much of a slap in the face as they used to be.

 

[Denithor]

Originally posted by: Sentry2
Depends on your sticks bud. What 4GB kit do you have and what motherboard are you gonna be running? 1600MHz will get you 200blck with out overclocking your ram.

On that 920 200blck x 20(stock multi with turbo off) will net you 4GHz. 3.8GHz should be cake. I would shoot for 3.9 - 4.0GHz....more if you're feeling brave and your cooling is up to the task.

Actually, DDR3-1600 should get you to 266blck without overclocking your RAM. Just use the 3x multiplier (probably called DDR3-800, will show up in CPU-z as a 2:6 ratio) which gives you:

266blck x 2 (ddr) x 3 (multi) = 1596mhz.

With a 920 that should get you as high as 5.32GHz. Hope you have LN2 cooling or something...

EDIT: What it boils down to is memory speed really isn't the limiting factor here either. DDR3-1333 can easily get you to 4.4GHz on a 920 without having to overclock the memory. Just use the multipliers correctly & you'll be good to go.

DDR3-800 = 133x2x3
DDR3-1066 = 133x2x4
DDR3-1333 = 133x2x5
DDR3-1600 = 133x2x6

To use these, simply take the blck you want to run your cpu at, multiply by two and then multiply by the multi that gets you closest to - but not over - your rated memory speed.

Example:
i7 920 @ 4GHz = 20x200blck
For DDR3-1333 memory, you want to run: 1333/(200x2)=3.33 so a 3x multi (DDR3-800).
This will give you an actual memory speed of 200x2x3 = DDR3-1200.
Note that running the next step up (DDR3-1066 or 4x multi) would require overclocking your memory: 200x2x4 = DDR3-1600 (which might work, depending on your memory, timings, and the volts you are willing to use).

 

[Blain]

The lower end i7's (920 & 940), have more limited memory multipliers than the better models.

 

[Denithor]

Limited on the low end or high end?

 

[Blain]

The "lower end i7 CPU's" (the 920 & 940), have more limited memory multipliers.

TechReport: Exploring the impact of memory speed on Core i7 performance
"<a target=_blank class=ftalternatingbarlinklarge href="http://www.techreport.com/articles.x/15967">We've split testing between a Core i7-920 and 965 Extreme due to the former's lack of official support for memory faster than 1066MHz.

Core i7-920 and 940 processors have a maximum memory speed of 1066MHz that motherboard makers haven't yet found a way to circumvent, but the 965 Extreme is free to use multipliers that run its memory bus at 1333, 1600, 1866, and even 2133MHz.</a>"

 

[Denithor]

Well, as shown on the chart at the bottom of that page, i7 920 supports DDR3-800 and DDR3-1066 officially - but has no problem running DDR3-1333 or DDR3-1600 in practice.

You just have to crank up the blck (and either drop the cpu multi as they did, or crank up the OC if you prefer) and the memory speed effectively goes up, according to the multi you've told it to use.

The i7 has a minimum multiplier of 12 so you can run up to 222blck without overclocking the cores. With a memory setting of DDR3-800 (effectively a 3x multiplier) that would yield a memory speed of 222x2x3=1330. If you run the higher memory multi of 4x (DDR3-1066 setting) you will get 222x2x4=1773. So you can max out most of the DDR3 memory on the market today without even having to overclock your cores. If you're willing to OC the cores a bit, you can easily go very, very fast on the memory speed - not that it will really make any true difference, but anyway...

i7 @ 3GHz: 12x250blck
DDR3-1066 setting = 250x2x4 = 2000mhz

 

[taltamir]

Originally posted by: Sentry2

Originally posted by: taltamir
save money on an i7? there are so many worthwhile upgrades and uses for money i would put before buying an i7... not to mention we are going to have the dual chanel version in a few months...

Are you using a velociraptor or a quality SSD? are you using 8GB of high speed DDR2 ram? very good overclocker mobo based on X48 or P45? a fast 45nm C2Q?
If the answer is yes to all the of above, than you should upgrade to an i7, but if that was the case saving money wouldn't be an issue.

Also, if that was the case than the i7 920 would not be an upgrade. The 920 is simply not cost effective (unless you intend to do zero over clocking, even than it is iffy...), there are plenty of cheaper and faster systems you could build from older intel CPUs. Only the 940 and 960 are worthwhile, but those REALLY cost too much.

The 920 is perfectly fine for overclocking...what are you trying to say about the 920's oc potential? The 940 is probably not worth double the cost for an extra 200MHz on the overclock( assuming it will even net you that when you pass 4GHz ) and the 965 as far as I'm concerned is a huge waste unless you're running phase.

Nobody said anything about saving money er by sticking with last gen...I think you have the wrong thread....?

The i7 920 is a great chip and the X58 is the superior Multi-gpu platform if he ever decides to go that route. DDR3 prices are also not as much of a slap in the face as they used to be.

I am saying, what if you get a higher end DDR2 and mobo for 775, and STILL save enough money to spend more than 300$ on a 45nm C2Q CPU from intel... and overclock it enough so it outperforms the i7...
Also avoids all the bugs of a new, and rushed, platform.