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PC3200 DDR memory @ > 200MHz speeds

J

jayoinoz

Junior Member
I've just bought an ASUS K8N-E Deluxe (I know, I know. Couldn't find a DFI LANParty vendor who'd ship to Ireland!) and now need memory for it (amongst other things). Going for s754 A64 3200+ (NC).

In Wesley Fink's review on Anandtech (Socket 754 Roundup, Part 3: Asus, Soltek & DFI) he uses PC3200 DDR and states, "When using an IDE drive, the K8N-E fared better, reaching a stable 271 FSB at 1:1 before failing boot.". 271MHz? That's closer to PC4400! Am I missing something?

Anywho, I've been looking at some Crucial Ballistix PC3200 (512MB CAS2) which I like the price of and am wondering what speeds I should "expect" to get out of it as I'm planning a wee bit of OC'ing. The PC3200 is rated CAS2 whilst the next Ballistix speed is PC4000 @ CAS2.5. PC4000 speeds at CAS2 would be nice out of the PC3200.

So what memory should I go for? Thanks all!
 
I would go for standard crucial as long as you arent trying to achieve "break neck" speeds with your memory.

The ballistix is nice, but not really worth the money. So unless money is of no object, save your money for a better GPU or CPU, or even just more memory
 
Shady06: D'ya mean I could (fingers crossed) get that out of the PC3200 Ballistix? Thanks for quick reply!

RadiclDreamer: Good advice. I suppose I won't be breaking 3GHz with this setup! I'll probably get Ballistix as I usually keep machines far longer than I should. Some breathing space would be nice. Typing on a PIII @ 866Mhz here! Did I mention I was lazy?
 
I would like to first note that your FSB is not directly related to your memory speed. The FSB is essentially a property of your processor. Your FSB is connected to a memory controller, which in turn connects to your memory via a memory bus.

Your FSB is not necessarily the same thing as your bus speed. If your motherboard is quad pumped then an FSB rating of 271MHz, has an effective frequency of 271x4 = 1084MHz and thus a total bandwidth of 1084x8= 8672MB/s (assuming a 64-bit data bus).

Your memory bus can then handle efficiently a total of 8672MB/s for a 1:1 ratio. This is an equivalent 542MHz memory running in dual-channel. So yes, in this case you can support DDR500 (PC4000) overclocked to ~542MHz, assuming your motherboard is using a quad-pumped bus.
 
The review says "...271 FSB at 1:1." In this case though the memory IS running @ 271MHz? Am I correct in understanding what the 1:1 means. I know it can be 5:6 or possibly other less. 271Mhz out of PC3200 though. Nice. That's what I'm getting at. Thanks BrentUnitedMem.
 
The ratio you are talking about is your FSB : DRAM ratio, which is a comparison of output between your bus speed (not necessarily FSB) and your memory bus speed.

These buses are not always on par with each other which is why we do not always see 1:1 (1:1 meaning that that the output is equivalent when we compare bus speed and memory speed) As a reult, your memory bus may be pumping data out at a different rate, which is why you may see a 5:6 ratio, for example.

Remember, your bus speed is composed as follows:

bus speed = FSB x (sampling rate)

where sampling rate is x1 for synchronous bus, x2 for double pumped bus, and x4 for quad pumped bus.

This ratio we are talking about, we are comparing bus speed vs memory speed. Not FSB vs. memory speed.

PC-3200 means that your memory has a theoretical bandwidth of 3200MB/s. In actuality, because of latency and noise, your performance is always lower than this theoretical value.

To answer your question: "The review says "...271 FSB at 1:1." In this case though the memory IS running @ 271MHz?"
=============================================
The memory is not necessarily running at 271MHz, your FSB is at 271MHz.

1:1 means that your bus speed (between your processor and memory controller) and your memory bus (between memory controller and memory modules) have the same bandwidth. And remember that for memory bus supporting dual-channel, your bandwith is essentially doubled. So by no means is this ratio a direct comparison of bus speed with memory frequency.


 
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