What DDR3 suits a 3.6+GHz Yorkfield build?

[Arbie]

I am planning a build based on a QX9650 and DDR3. I have read the 2007-8 Anandtech articles on RAM and FSB with interest and appreciation if not with complete understanding.

My minimum goal is a 3.6GHz Yorkfield with 4GB fast RAM on air cooling 24/7. The PC will probably be in service 5 years, so my budget is flexible. I'll spend extra to attempt 3.8GHz or even 4.0GHz, which is the max I hope for; hence the unlocked CPU. I'd like to use 2x2GB modules to keep the option open for 8GB later (only WinXP Pro 32 for now) - but not if that kills memory subsystem performance. I value the latter for RAR / UNRAR and some video encode / decode. I want an X48 mobo and will use an ASUS P5E3 Premium, or the Rampage Extreme if it comes out in the next couple months. I am heat-limited in my computer room so I'll skimp on the graphics card (not so important to me) and expend my thermal budget on the rest of the platform.

==> The biggest gray area now is: what RAM? What speed, latencies, and configuration? I must be careful here since RAM affects other things and DDR3 gets very expensive in the highest speed ranges.

I can't find any articles that talk in detail about fast Yorkfields and DDR3. There are some rig reports, but these are usually OC benches and not 24/7 practical, or are dangerously overvolted, water cooled, etc. I can't learn much just from these examples, although if I'm lucky I'll something suitable that I can duplicate. But I would rather know what I'm doing.

Any advice on the best choices and/or setup tips will be greatly appreciated.

Thanks,

Arbie

 

[DSF]

For what it's worth, there's DDR2 fast enough to take a chip up to 4.0GHz. I suppose if you're spending $1000 on a CPU you may as well go all out though.

 

[LittleNemoNES]

IMO DDR3 is not worth it yet. It will be early next year, though.

 

[BTRY B 529th FA BN]

DDR2 1066. I don't think you'll get even close to 533 fsb to run it 1:1 sync unless you have some real talent, which we'd appreciate if you'd share with us. Anything under that is useless headroom.

 

[Arbie]

Originally posted by: BTRY B 529th FA BN
DDR2 1066. I don't think you'll get even close to 533 fsb to run it 1:1 sync unless you have some real talent, which we'd appreciate if you'd share with us. Anything under that is useless headroom.

Thanks for the input. BTRY B - I'm very interested in what you said, because I don't want to pay for useless headroom. But I don't yet know enough to understand your logic in one jump. Can you explain the point more step-by-step? Are you saying that nobody needs anything faster than DDR2-1066 unless they are getting to 533 MHz bus (?). I thought the RAM speed would be matched to 4x the bus to get 1:1...

Thanks,
Arbie

 

[BTRY B 529th FA BN]

The best place to learn some of this is in this thread here:
http://forums.anandtech.com/me...=2057083&enterthread=y
but be careful. Cross check the info, I ended up finding a mistake in the OP, which was brought to the OP's attention and corrected so if you are not understanding something in the guide, be sure to ask anyone if the info's right.

 

[myocardia]

Originally posted by: Arbie
Are you saying that nobody needs anything faster than DDR2-1066 unless they are getting to 533 MHz bus (?).

Yes, that's correct. PC8500 RAM is rated for a maximum of 533 Mhz/1066 Mhz DDR. If you run it 1:1 with a QX9650, it runs at 333 Mhz/667 DDR. Now, just so you know, DDR3 runs at a minimum of 2:1, so running DDR3 as slow as it will run with a QX9650 will net you 667 Mhz/1333 DDR*. Now, the larger numbers might sound good, but the difference in performance isn't noticeable at all, unless you're running a benchmark, and even then, it's only a couple of percent faster (less than 5%, in other words).

I thought the RAM speed would be matched to 4x the bus to get 1:1...

No, the RAM runs at exactly the same speed as the FSB, when ran @ 1:1, that's why the term 1:1 is used; they're identical.


*It's considerably more complicated than that in real life, but that should be enough info, for someone who's having a hard time understanding the basics.

 

[Arbie]

Thanks very much myocardia, that's a BIG help. Maybe you can answer, confirm or comment on these points to finish it off... I think they'll be quick answers for you.

I expect to have an Asus X48 board with an FSB of 400 or 450MHz.

? For DDR3 to operate at 2:1 (its minimum - I didn't know that!) at FSB 400 / 450 it would have to be at least DDR3-1600 / DDR3-1800.

? DDR3-1333 makes sense only at FSB 333 or less. That means it won't support overclocking the Penryn duals or quads at all.

? DDR3-1600 in 2x2GB is barely within my budget. If I did buy it, would I need to worry about whether it will "really" meet 1600 when two modules are used?

? Is 2x2GB a more benign case than 4x1GB? I've heard that the latter will definitely hurt latencies compared to 2x1GB.

? DDR2-1066 is more than fast enough for an FSB of 400 or 450MHz. RAM faster than this may let just me tighten the timings.

? Given the cost of the 1600+ modules, DDR3 has little home or even gamer appeal now. The comments I see about its technical superiority are either referring to the highest speed grades or to future potential, possibly with with Nehalem.

Thanks again -

Arbie

 

[n7]

1:2 isn't a minimum by any means.
Nothing wrong with 3:5 or 5:8, etc.

But it's a nice ideal on DDR3 platforms, sure.

If you are actually getting a QX9650, you don't need to worry about high FSB annoyances, since you've got an unclocked multi.

So you could easily OC, & also keep RAM 1:2 w/o issues.

But honestly, right now, DDR3 is so hard to recommend as it's really not a good value yet.
And a QX CPU is an even worse value.

Right now, i'd be suggesting a Q6700 with a solid P35/X38/X48 DDR2 mobo, w/ 8 GB DDR2.

And no, i'm not kidding.

You get flexible overclocking due to the high 10x multi on the Q6700 (alleviates all the headaches w/ Yorkies & low multis), still great mobo choices, & you can get tons of fantastic DDR2 for cheap.

Not saying you should copy my rig in sig per say...but i'd say it makes my point at least.

Then worry about DDR3 when Nehalem when it hits, as it just simply isn't worth going the DDR3 route just yet.

Considering we're looking at a whole new socket, etc. with Nehalem, & much lower DDR3 pricing by then, i really believe it makes sense to wait, as you can enjoy a very fast DDR2 system today for cheap, & then sell & get into DDR3 when it really makes sense...

Just my $0.02.

 

[Arbie]

Thanks, n7. That helped too.

I realize that the QX9650 isn't a good value at its MSRP, but for a couple weeks there new ones had dropped to $750 on Ebay. The difference between those and Q9550 (I want Penryn for several reasons) was only about $200, since the new Yorkfields haven't dropped at all.

Now, suddenly, the QX9650 is way back up. That changes things again - but I'm in no hurry.

I'm still learning, which is fun. I can say that after reading many, many articles and threads on many sites, I am coming back to Anandtech first for in-depth material. This year's motherboard / RAM articles in particular have been great.

I'm sure I'll be back with more questions after I digest what I've picked up in the past couple days.

Arbie