ddr2-800 or ddr2-1066?

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00ber_m00

Limp Gawd
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Jul 10, 2004
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Sorry if this has been asked and answered but I've read through several threads and have not found a full answer to this question. I rarely ever post because most of my questions are answered somewhere but alas here I am. From what I understand the Conroe stock FSB is 1066mhz but I see most people planning their builds with 800mhz ddr2. Won't this be running the processor slower than it is designed? I realize that the 1066mhz costs twice as much as the 800mhz, but is that the only reason? It seems odd to me that so many people plan to run the processor slower than it is designed to be run so I believe I'm missing something. Thanks.
 
dual channel DDR2-800 = 12.8GB/s bandwidth
1066MHz FSB = 8.5GB/s bandwidth

That leaves 4.3GB/s bandwidth for other functions of the chipset, PCI-E cards and PCI bus masters. :p
 
Sorry, I'm not quite sure I understand what you mean. pc2-8500 (1066mhz) ram can't run in dual channel?
 
pxc said:
dual channel DDR2-800 = 12.8GB/s bandwidth
1066MHz FSB = 8.5GB/s bandwidth

That leaves 4.3GB/s bandwidth for other functions of the chipset, PCI-E cards and PCI bus masters. :p
Click to expand...
Not to "highjack" this guys thread, However since were on the subject i'll ask: I plan to OC my x6800, should I get DDR2-800, or DDR1000? Im not understanding how intel rates there FSB. I know its "quad" pumped, but...............
 
00ber_m00 said:
Sorry, I'm not quite sure I understand what you mean. pc2-8500 (1066mhz) ram can't run in dual channel?
Click to expand...
Of course it can.

Why not try to explain why you believe that dual channel DDR2-800 is somehow limiting a 1066MHz FSB CPU? Don't be shy with the math to demonstrate your view. :p
 
DDR2-667 is the stock clock speed for ConroeRAM, correct? DDR2-800 gives some more headroom while DDR2-1000+ gives a bunch of headroom.
 
oh dont be mean! :cool:

ddr-800 is 6400, right?
6400x2 = 12.8
in DUAL channel.
but, if you will not use DUAL channel, then yes, one stick of ddr 1066 or what not would be better.

p.s. dual channel can be thought of as RAID-0
 
Why not try to explain why you believe that dual channel DDR2-800 is somehow limiting a 1066MHz FSB CPU? Don't be shy with the math to demonstrate your view
Click to expand...

At the risk of sounding foolish... 800 < 1066
 
00ber_m00 said:
At the risk of sounding foolish... 800 < 1066
Click to expand...

The Conroe's FSB is 266x4. DDR2-800 is 400x2. The raw clockspeed is what you look at. DDR2-533 would actually match the frequency of the Core 2 Duo's front side bus.
 
00ber_m00 said:
At the risk of sounding foolish... 800 < 1066
Click to expand...
So a dual channel 800MHz effective memory bus (16 bytes wide) has less bandwidth than a 1066MHz effective FSB (8 bytes wide)? Interesting. :p
 
The Conroe's FSB is 266x4. DDR2-800 is 400x2. The raw clockspeed is what you look at. DDR2-533 would actually match the frequency of the Core 2 Duo's front side bus
Click to expand...


gotcha, i think that clears it up for me...



and pxc, i'm not sure why you're assuming i wouldn't be running the 1066 in dual channel
 
pxc said:
dual channel DDR2-800 = 12.8GB/s bandwidth
1066MHz FSB = 8.5GB/s bandwidth

That leaves 4.3GB/s bandwidth for other functions of the chipset, PCI-E cards and PCI bus masters. :p
Click to expand...

I'm no super genius nor am I a noob but can you explain what this can possibly mean? I mean, they'll run together but at a different ratio than 1:1 but saying it leaves 4.3GB of bandwidth for other functions of the chipset? wtf?

pxc said:
So a dual channel 800MHz effective memory bus (16 bytes wide) has less bandwidth than a 1066MHz effective FSB (8 bytes wide)? Interesting. :p
Click to expand...

So saying 800 > 1066 automatically means he mean dual channel 800 and a 1066 fsb? Perhaps I thought he was just talking about ddr2 800 vs ddr2 1066? Interesting.
 
oh my.. its like three conversations at once in this one thread....
:confused:

oh well,
dual channel is raid-0 so you have double the throughput and twice the speed.
and fsb of 1066 (if devided in half) will use ddr 533 (because we all know that a dual channel ddr2 533 = 533x2 = 1066)

if you want to OC then its a different story, that why most people go for the DDR2-800
that way they can lower the multiplier and raise the memory speed by a bunch to oh say 400... even more on some chips since tight timings are not that important to conroe...
 
Megalomaniac said:
oh my.. its like three conversations at once in this one thread....
:confused:

oh well,
dual channel is raid-0 so you have double the throughput and twice the speed.
and fsb of 1066 (if devided in half) will use ddr 533 (because we all know that a dual channel ddr2 533 = 533x2 = 1066)

if you want to OC then its a different story, that why most people go for the DDR2-800
that way they can lower the multiplier and raise the memory speed by a bunch to oh say 400... even more on some chips since tight timings are not that important to conroe...
Click to expand...


Yep, Conroe FSB is 266 quad-pumped, 266x2=533mhz, x2 = 1066FSB. I went for OCZ 2x1GB Platinum XTC DDR2-PC26400 (800mhz rating) RAM with 4-5-4-15 stock timings for my Conroe overclock. That way, RAM shouldn't be my limiting factor, as on my E6600 I could go to 3600mhz on the CPU (9x400) before even having to overclock the RAM if I were going for a 1:1 RAM divider :D!
 
so is it safe to say any ddr2 800 pc2 6400 will get you to 3.6ghz at 1:1 ratio assuming the cpu can reach 3.6ghz and we're talking about the E6600 meaning like GT said 9x400

is this correct?

so would that make it, if you buy ddr2 800 regardless of brand you can have a 3600mhz E6600 with 1:1 and anything over that on 1:1 depends on the ability of the ram to oc
 
Here's a clear cut explanation for those who don't get it.

Conroe will run at 1066 fsb.

Let's say the OP chooses ddr2 800. He'll get dual channel effective 1600. Much more than fsb so he can raise the fsb up to 1600 within the ram's spec.

Let's say he got a E6600 which is a 2.4 with a 9x multiplier. Now here's the tricky part. Intel quad pumps their bus. So the 1066 is actually 266. 266 x 9 = 2.4. So let's say you want to OC to the ram's full spec. Well, ddr is double so ddr2 800 is actually 400. 400 time the 9x multiplier = 3.6.

Now let's say you have a super sweet chip and some massive cooling and want to go for a 100% oc. That's where the ddr 1066 comes in. If you run those in dual channel, you have 2133 which is twice the CPU's native fsb. If you can raise the fsb that high, you get double the cpu frequency.

To OP, choosing ddr2 1066 over 800, the reasons might be just extra room to OC even more if a user can go higher or perhaps the latencies might be lower on the higher spec'ed ram.

To Gun_Strife, yes, any ddr2 800 spec memory SHOULD get you to 3.6 if the CPU allows it. However like I said just above, the latencies might be better with higher spec'd ram. While a higher speed ram might have higher latencies at their spec'd speed, lowering the clock of let's say, ddr2 1066 to ddr2 800 to reach 3.6 might give you better latencies.
 
awesome TeknoZX
that helps alot
so when buying ram to oc these cpus any ddr2 800 should get you 3.6ghz the only real diffrences are price timings and potential to oc
sorry for sounding stupid or repeating myself but I had no idea of the way intel works
 
Good reading. I've been an AMD person since the early Athlon days and am thinking about jumping ship for the Conroe and am really trying to catch up with the way Intel does their FSB and ram speeds. This thread answers alot for me.

Shawn
 
Nice read indeed...Also an AMD user since thunderbird days. Thinking about jumping ship november...Now, all I need are guinea pigs to test all the best mbs and conroes out..don't forget memory...
 
Thanks for the info everyone. I understand now. The whole quad pumping thing threw me off. I've been an AMD guy for a long time...I think my last intel processor was a p2.
 
lol seems alot of us are unfamiliar with intel, I personally have never had an intel system
but there is absolutley no reason to go amd for an upgrade at the moment
 
newls1 said:
Not to "highjack" this guys thread, However since were on the subject i'll ask: I plan to OC my x6800, should I get DDR2-800, or DDR1000? Im not understanding how intel rates there FSB. I know its "quad" pumped, but...............
Click to expand...

If you can afford the x6800 go for DDR2-1000 or even DDR2-1066.
 
TeknoZX said:
Here's a clear cut explanation for those who don't get it.

Conroe will run at 1066 fsb.

Let's say the OP chooses ddr2 800. He'll get dual channel effective 1600. Much more than fsb so he can raise the fsb up to 1600 within the ram's spec.

Let's say he got a E6600 which is a 2.4 with a 9x multiplier. Now here's the tricky part. Intel quad pumps their bus. So the 1066 is actually 266. 266 x 9 = 2.4. So let's say you want to OC to the ram's full spec. Well, ddr is double so ddr2 800 is actually 400. 400 time the 9x multiplier = 3.6.

Now let's say you have a super sweet chip and some massive cooling and want to go for a 100% oc. That's where the ddr 1066 comes in. If you run those in dual channel, you have 2133 which is twice the CPU's native fsb. If you can raise the fsb that high, you get double the cpu frequency.

To OP, choosing ddr2 1066 over 800, the reasons might be just extra room to OC even more if a user can go higher or perhaps the latencies might be lower on the higher spec'ed ram.

To Gun_Strife, yes, any ddr2 800 spec memory SHOULD get you to 3.6 if the CPU allows it. However like I said just above, the latencies might be better with higher spec'd ram. While a higher speed ram might have higher latencies at their spec'd speed, lowering the clock of let's say, ddr2 1066 to ddr2 800 to reach 3.6 might give you better latencies.
Click to expand...

A couple of small problems. The FSB and Memory controller aren't *locked unless you lock them. FSB isn't limited by the memory controller or RAM's speed otherwise. Intel uses ratios on all off the newer boards since at least the i8xx series. ATI's is fully independent.

Ratios
1:1 800:800 DDR2 400 X 2 or one single DDR2 800
3:4 800:1066 4x00 modles, DDR2 533 X 2
1:1 1066:1066 ""same
4:5 1066:1333 DDR2 667 X 2
4:6 1066:1600 6X00 DDR2 800 X 2
5:6 1333:1600 8X00 '' '' the real XE model.
Stock settings. These can be *Unstrapped* meaning unlocked and the overclocking setting combinations are too many to list.

For all the numbers except "1" the ratios for FSB are merely 266.7 X x = xx. 4:5 is 4 X 266.7 to 5 X 266.7 as it looks to the Clock Gen. It's all a matter of timing and staying in time.

Right now there is no support for DDR2 1066 or 1000;) It will only be needed for Extreme Overclocking. According to the guys at Xtreme systems, 400MHz FSB is not LOL!

I'm getting an E6600 and DDR2 800 with the main goal of only reaching 3GHz I saw the 3GHz E6600 vs 3GHz Opty. Anything above that is gravy. I figure an almost as easy 3.3GHz is more than enough. Don't even care about 3.6GHz:)
 
Ok so if I'm understanding this correctly...

If I bought an E6700 (266x10 = 2660 MHz), I could go as low as DDR2-667 and still be able to OC to 3.3 GHz (667/2 = 333 x 10 = 3330 MHz) at a 1:1 ratio. I really want to get CAS 3 memory (I know it probably won't make that much of a difference but it'll satisfy my e-penis) so it's either spend a gross 470 on the DDR2-800:
http://www.newegg.com/Product/Product.asp?Item=N82E16820145035

or spend less than half on the DDR2-667:
http://www.newegg.com/Product/Product.asp?Item=N82E16820146093
 
thenickmix said:
Ok so if I'm understanding this correctly...

If I bought an E6700 (266x10 = 2660 MHz), I could go as low as DDR2-667 and still be able to OC to 3.3 GHz (667/2 = 333 x 10 = 3330 MHz) at a 1:1 ration. I really want to get CAS 3 memory (I know it probably won't make that much of a difference but it'll satisfy my e-penis) so it's either spend a gross 470 on the DDR2-800:
http://www.newegg.com/Product/Product.asp?Item=N82E16820145035

or spend less than half on the DDR2-667:
http://www.newegg.com/Product/Product.asp?Item=N82E16820146093
Click to expand...

No, you want the RAM actually faster than the FSB. That way PCI-E, DMA, DMI (I/O) and etc.. doesn't steal bandwidth from the FSB. This is only important when the CPU is or close to being Maxed out and the PCI-E is working hard, games are a good example.

I'm only going with DDR2 800 CAS4 4-4-4-12 for that reason. Intel showed the Conroe kicking ass with 5-5-5-15 stock settings.
 
Donnie27 said:
No, you want the RAM actually faster than the FSB. That way PCI-E, DMA, DMI (I/O) and etc.. doesn't steal bandwidth from the FSB. This is only important when the CPU is or close to being Maxed out and the PCI-E is working hard, games are a good example.

I'm only going with DDR2 800 CAS4 4-4-4-12 for that reason. Intel showed the Conroe kicking ass with 5-5-5-15 stock settings.
Click to expand...

In my post, I was talking about a 1:1 ratio because with ram that fast, why not? I mean, isn't 1:1 the best and other ratios just there so you can overclock higher if the ram is limiting you? I can't imagine why you'd want to use anything other than 1:1 with memory that fast unless you OC to the extreme and the ram seems to be holding you back. :)

And wtf is with this talk about devices stealing bandwidth from the FSB? Did I seriously miss something? Was this such a big issue and I've been ignorant about this this for years? :confused:

Devices...DMA isn't even a device...stealing bandwidth...from the FSB.. so that's why you want faster memory....even though it won't be running as fast as spec...uh huh ;)

So you want 3ghz with a E6600? Let's see, 3ghz divided by a 9x multiplier gets you 333mhz. That base times 4 = 1333mhz FSB. So you need ddr2 667 running in dual channel. But you want ddr2 800. So if you go 1:1, you'll be lowering the speed of the ram to 667. that extra 133 is wasted...not saved for "other devices."

But you want to run the ram faster than the cpu...so you use a different ratio.

please..PLEASE educate me on this business of devices like DMA stealing bandwidth from the FSB. If it's such a big deal, I need to learn because I have no idea what you're talking about. Aside from the fact that data does travel along the fsb and such but bandwidth stealing....no clue..
 
TeknoZX said:
In my post, I was talking about a 1:1 ratio because with ram that fast, why not? I mean, isn't 1:1 the best and other ratios just there so you can overclock higher if the ram is limiting you? I can't imagine why you'd want to use anything other than 1:1 with memory that fast unless you OC to the extreme and the ram seems to be holding you back. :)

And wtf is with this talk about devices stealing bandwidth from the FSB? Did I seriously miss something? Was this such a big issue and I've been ignorant about this this for years? :confused:

Devices...DMA isn't even a device...stealing bandwidth...from the FSB.. so that's why you want faster memory....even though it won't be running as fast as spec...uh huh ;)

So you want 3ghz with a E6600? Let's see, 3ghz divided by a 9x multiplier gets you 333mhz. That base times 4 = 1333mhz FSB. So you need ddr2 667 running in dual channel. But you want ddr2 800. So if you go 1:1, you'll be lowering the speed of the ram to 667. that extra 133 is wasted...not saved for "other devices."

But you want to run the ram faster than the cpu...so you use a different ratio.

please..PLEASE educate me on this business of devices like DMA stealing bandwidth from the FSB. If it's such a big deal, I need to learn because I have no idea what you're talking about. Aside from the fact that data does travel along the fsb and such but bandwidth stealing....no clue..
Click to expand...

Not wasted at all=P

Please note, I said the the Processor is maxed out or at 100% not common except for games, DMA via DMI calls to memory, plus PCI-E to memory will steal Bandwidth from the CPU=P That is with the RAM and Processor 1:1 like 533MHz X 2 RAM and 1066MHz FSB. Or 1333MHz FSB to 667 X 2 RAM. DMI and DMA are links, I didn't say devices. These make INDEPENDENT calls or reads and writes to RAM. Direct Memory Interface and Direct Memory Addressing. They fight for the same bandwidth and any HUB works. 2GB DMI and 4GB per direction at least PCI-E will steal bandwidth. Intel's Memory Controller HUB is just that, a HUB. Honestly now, the Processor doesn't need to be maxed out to feel the pinch!

The FSB is but only one link like an R45 cable connected to a Hub, the DMI (DMA within that) and PCI-E connects the same way.

When I965 says it support DDR2 800, it is NOT running 1:1 but 4:6. A good overclocked Ratio might be 6:8, hehehe! 1:1 used to be the best on i875 and etc... because it doesn't have advance buffers, DMI and etc.. that i945 (some say i925) has. The motherboards were supposed to be tuned to get the most out RAM, PCI-E and DMI, not just the processor. If ATI's board is Debugged, it will truely kick ass. The extra Bandwidth is there to fully support 48 PCI Lanes. Can't do that with Processor and RAM running 1:1.

1:1 doesn't leave 4GB in each direction for PCI-E or what little the DMI might need. Unless you're running RAID 5 LOL! HDD traffic and CPU usage goes up for that since it is software based. DMI then puts some if that 2GB of bandwidth to use, see a problem now?

DDR2 800 is already running at 1600MHz effective and if the processor does 1600MHz I'd love the RAM to do 2133 at least. So 1066 would come in handy then. You'd have to stress the system to see a real difference though. I'm not even thinking about overclocking that high. I might like to see about 1333 to 1880 though! Wasted, I think not.
 
Not to derail the thread...but does anyone know if they will be changing sockets/chipsets for kentsfield? What I'm wondering is maybe I should get DDR2-1000, that way if they release a kentsfield with a 1333 FSB, I could still overclock the RAM to say 400 MHz, and still have the overhead you guys are saying is necessary. I'd like to for once not have to buy a new mobo and RAM with my next processor upgrade (probably gonna get a quad-core kentsfield that will be running a stock 3.0 GHz if it exists, and then OC it to a safe 3.3, since all I plan on doing with my Conroe is OCing up to 3.0.)
 
The SPD of DDR2 1066 ram is set to DDR2 800 by default; I believe...Therefore you should be able to use it. Although the EPP for Corsair's mem is for Nforce 590. From reading the review its not very useful at all. But if you can afford it PC8500/DDR2 1066 should be ideal for C2D

Also look at the link. As you can see PC8500 does better with C2D then using PC6400 with tighter timing. In a nutshell FSB > Timing. Regardless of the differences between tighter timing of DDR2 667 and DDR2 800 what triumphs is DDR2 1066. Anything else is trivial at best.
 
thenickmix said:
Ok so if I'm understanding this correctly...

If I bought an E6700 (266x10 = 2660 MHz), I could go as low as DDR2-667 and still be able to OC to 3.3 GHz (667/2 = 333 x 10 = 3330 MHz) at a 1:1 ratio. I really want to get CAS 3 memory (I know it probably won't make that much of a difference but it'll satisfy my e-penis) so it's either spend a gross 470 on the DDR2-800:
http://www.newegg.com/Product/Product.asp?Item=N82E16820145035

or spend less than half on the DDR2-667:
http://www.newegg.com/Product/Product.asp?Item=N82E16820146093
Click to expand...

I bought some of this stuff:
http://shop3.outpost.com/{QQSqh9SOl...m+ivfDdHQ**.node3?site=sr:SEARCH:MAIN_RSLT_PG

The corsair is to be a bit better, but I believe there is enough headroom in the OCZ stuff, and much cheaper! Also, Outpost runs rebate specials quite often, they were $150AR not too long ago.
 
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