1333MHz FSB Proc with DDR2 1066 -- What Happens?

[Weatherton]

I'm currently debating between the Q6600 and the E8500. I think I like the Asus P5Q-e motherboard, but I want to get some affordable RAM. Since I'm planning to get 2x2GB of DDR2-1066, I'm curious; what would that due to the clock speed / multiplier for the E8500 (since it has a native FSB of 1333).

I seem to recall that the newer Intel procs don't even really have a FSB anymore due to the integrated memory controller. I'd appreciate any overall clarification in addition to specfically addressing my concern with DDR2-1066.

P.S. - I don't overclock; I had a bad experience.

 

[cubeless]

it works fine... however, it is officially 'overclocked' since the spec doesn't recognize 1066 memory...

u have to set it up in the bios... u use a memory divider...

 

[myocardia]

Okay, the short answer is the slowest RAM you can use with the E8x00's without overclocking the RAM is DDR-667, also known as PC5300. If you want a more in-depth answer, I can give you one.

 

[Weatherton]

Originally posted by: myocardia
Okay, the short answer is the slowest RAM you can use with the E8x00's without overclocking the RAM is DDR-667, also known as PC5300. If you want a more in-depth answer, I can give you one.

I'd love a more in-depth answer (I took some processor design courses in college a few years ago). Thanks!

 

[Markfw]

1333 FSB = 333 mhz speed quad pumped. 1066 DDR2 ram is 533 mhz double data rate. So you are actually running the ram under speed if everything is set to default in the bios.

Wonderfully confusing, isn;t it !

 

[nerp]

Yeah it's pretty confusing, especially if you suck at math like me.

Good rule of thumb is that if you're NOT overclocking, you can just use DDR2-667 at stock settings.

You DON'T need to run DDR2-1066 to take full advantage of a high FSB cpu. If you ARE overclocking, though, you'll want faster memory so you can run the memory as close to synch with your FSB as possible. Sorta.

Thing is, you can always run memory on a divider and with intel setups this won't really be such a negative on performance. Say you overclock your PC and the FSB is at 475. Running DDR2-800 at 1:1 would overclock that memory by 150mhz -- not all DDR2-800 can run at DDR2-950 without voltage increases or at all. But you can easily ramp down the memory speed while OCing the CPU and FSB and the memory will be close to spec. This works just fine. And the performance difference isn't really noticable. In fact, it may be nonexistant.

 

[Idontcare]

Originally posted by: cubeless
it works fine... however, it is officially 'overclocked' since the spec doesn't recognize 1066 memory...

That statement makes no sense on a number of levels. Things cannot be officially overclocked since the clockspeed is defined as whatever the seller wishes it to be defined as. If the seller defines the memory to be a product that operates at 1066 then that is the products clockspeed, not overclock speed. Overclocking is something the consumer does, not the seller.

Just because DDR2-1066 does not formally exist as a spec does not mean memory chips capable of operating at DDR2-1066 speeds and sold as operating at those speeds are somehow overclocked.

 

[Tempered81]

Originally posted by: Markfw900
Wonderfully confusing, isn't it !

+1

 

[Tempered81]

your e8500 at stock FSB is 333mhz. 333 x 4 = 1333mhz (1333 is native FSB of your mobo).

The ram you're looking at is pc8500 1066 ram. this is actually DDR2 (533mhz x 2) 1066.

Pc5300 667 ram is actually DDR2 (333mhz x 2) 667. This speed is suitable for the 333mhz FSB the stock E8500 runs at.

Overclocking? The e8500 could run at 533mhz FSB (aka 533 x 4 = 2132mhz on the motherboard) When they say a mobo has native 1600mhz FSB, this means 400mhz x 4. an E8500 at 400mhz times a 9.5x multiplier would be running at a speed of 3.8Ghz. The motherboard would be running at 1600mhz, and the ram would be running at 400mhz (400 x 2 = 800mhz DDR2).

Overclocking scenario #1:

1. Cpu is an E8500 overclocked from 333mhz x 9.5 to 400mhz x 9.5 and is running at 3.8Ghz. It is using a 400mhz (1600mhz) FSB.

2. Motherboard is an Asus P5q-E with native 1333mhz (333 x 4) FSB. It is overclocked to 1600mhz FSB (400mhz x 4).

3. Ram is PC2-8500 (1066mhz) DDR2. It is using a 1:1 divider (not entirely necessary in this case, but not the point) with the motherboard and is running at 400mhz (400mhz x 2 = 800mhz effective ddr2 rate).

 

[myocardia]

Okay, today I have time for a more in-depth answer. Now, Intel's processors' FSB's run @ 1/4 th the speed that Intel claims. Intel isn't really lying, because they actually transfer data 4x per clock cycle, meaning that they perform exactly as they would if they were running 4x as fast. It works exactly like DDR or DDR2 RAM, where the DDR or DDR2 speed is actually twice as fast (in the instance of DDR), or 4x as fast with DDR2, as the actual speed that the RAM is running at. To figure out the minimum speed DDR2 that any processor needs, just use jaredpace's instructions above. For instance, an E8500 requires at least DDR667, and a Q6600 requires at least DDR533, also known as PC4200.

 

[VirtualLarry]

Originally posted by: myocardia
It works exactly like DDR or DDR2 RAM, where the DDR or DDR2 speed is actually twice as fast (in the instance of DDR), or 4x as fast with DDR2, as the actual speed that the RAM is running at.

Pretty sure both DDR and DDR2 run at 2x the clock speed, no?

 

[Idontcare]

Originally posted by: VirtualLarry

Originally posted by: myocardia
It works exactly like DDR or DDR2 RAM, where the DDR or DDR2 speed is actually twice as fast (in the instance of DDR), or 4x as fast with DDR2, as the actual speed that the RAM is running at.

Pretty sure both DDR and DDR2 run at 2x the clock speed, no?

Actually its true.

http://hubpages.com/hub/DDR1__...avigating_The_RAM_Maze

PC3200 (DDR-400 SDRAM); Clock Speed: 200MHz, Data Rate: 400MHz, Throughput 3200MB/s

PC2-6400 (DDR2-800 SDRAM); Clock Speed: 200MHz, Data Rate: 800MHz, Throughput 6400MB/s

PC3-12800 (DDR3-1600 SDRAM); Clock Speed: 200MHz, Data Rate: 1600MHz, Throughput 12.80GB/s

So we see DDR runs as advertised - double or 2X the memory's clock. DDR2 is double double, or 4x the memory's clock. And DDR3 is double-double-double, or 8x the memory's clock.

In all cases the underlying clock here is operating at the same paltry 200MHz (hence the shitty latency improvements in terms of absolute nanoseconds) but the data-rates have risen from 400MHz (DDR-400) to 1600MHz (DDR3-1600) so hence the throughput has risen from 3.2GB/s to 12.8GB/s in this example.

 

[Markfw]

uhhh, excuse me, doesn't PC-6400 have a clock speed of 400 ? And doesn't PC3-12800 run much higher than 400 ?

 

[Idontcare]

Originally posted by: Markfw900
uhhh, excuse me, doesn't PC-6400 have a clock speed of 400 ? And doesn't PC3-12800 run much higher than 400 ?

Nope. What you are confusing is the actual clockspeed that the memory chip function at versus what the "pumped" clockspeed is.

Kinda like how people interchangeably refer to the FSB as being 1333MHz or 4x333. The underlying clockspeed of the FSB clock is indeed 333MHz in this case, but the data cycle is 1333MHz as it is quad-pumped.

So yes, sadly as it seems, the transistors in our fancy shmancy 2008 DDR3-1600 chips are operating no faster than the transistors in our 4 yr old DDR-400 chips. But the signal/noise has been cleaned up so much, despite the significant operating voltage reductions, that they now tease out 8 bits of data on every clock cycle.

The primary benefit of DDR3 is the ability to transfer I/O data at eight times the speed of the memory cells it contains, thus enabling faster bus speeds and higher peak throughput than earlier memory technologies. However, there is no corresponding reduction in latency, which is therefore proportionally higher.
http://en.wikipedia.org/wiki/DDR3

 

[Markfw]

My bios says my memory is running at 400 mhz, and so does cpu-z.

 

[Idontcare]

Originally posted by: Markfw900
My bios says my memory is running at 400 mhz, and so does cpu-z.

You are misinterpretting what your BIOS and CPU-z is saying is running at 400MHz.

They are letting you know the memory bus is operating at 400MHz. It is assumed that you understand the memory itself runs at 1/2 the bus.

The key difference between DDR and DDR2 is that in DDR2 the bus is clocked at twice the speed of the memory cells, so four bits of data can be transferred per memory cell cycle.

Thus, without speeding up the memory cells themselves, DDR2 can effectively operate at twice the bus speed of DDR.

http://en.wikipedia.org/wiki/DDR2_SDRAM

Were your BIOS to tell you your FSB operates at 1600MHz you'd know that meant the FSB really operates at 400MHz but that it was quad-pumped. You wouldn't look at the 1600MHz FSB number and think "go'dam and it's quad-pumped on top of that, so 4x1600MHz!!! Oh yeah baby!!!".

Really, I'm not trying to pull your leg here. Your DDR2-800 and DDR3-1600 memory really operate at 200MHz when you get down to the chip-level operating frequency. You are confused because the situation was setup to confuse you by the marketing experts who decided DDR2 and DDR3 speeds would be based on referencing how fast DDR memory would need to operate to give you the same bandwidth. (to convince you that you are buying faster and faster memory with each generation)

It is faster if bandwidth is all you care about, but if you care about latency in terms of nanoseconds and the like then we are hardly better today than we were 4 years ago. (although chipsets have gotten better, IMC's and the like, so total memory access latencies are better system-wise than 4yrs ago) And voltage has gone down markedly and bit density has increased markedly so its hard to feel too jaded when you learn some truths.

Marketing, it'll get you every time. Now get out their and buy your 12.8GHz i7 (quad-core 3.2GHz of course).

 

[n7]

Idontcare is correct.

And OP, what would happen is ratios.

If you get the Q6600 & DDR2-1066, & were running stock, you'd be running 1:2.
If the E8500, then 5:8.

 

[FalseChristian]

I'm running my fsb at 1750MHz so that's 875MHz DDR2. That's why I bought DDR2-1066 so I could get past the 1600MHz fsb without having to overclock the RAM, know what I'm sayin'?

 

[cdnbum88]

Ok, newbie'ish to OCing.

I have a 680i LT with a Q6600 and just bought 4 gig of OCZ DDR2 8500 for my rig.

If I want to clock my 2.4 to say 3.2 for a nice round number, what would you recommend I set my bios to get the most out of the 1066 memory?

Like it has been noted in the thread when I link and leave my multipler at 9x and then change the fsb to 1400 say, then the memory goes there and it won't boot, since the memory can not handle 1400 obviously right?

Thoughts, recommendation.

Based on my sig, if anyone has a similar setup and would offer some more robust OCing options, I am open.

Thanks