Posted on 02/02/2008 1:07:59 PM PST by pctech
I am in need of some advice about newer Dual Core and Core 2 technologies.
My older Pentium 4 systems (can you believe I'm calling that old?) seemed to be easier to work with when I had to match up processors to memory. You had processors that had to match up with system bus.
If a processor has a FSB of 800 MHz, you had memory that was clocked at 400 MHz. The DDR memory was multiplied by 2 and it worked.
If a processor has a FSB of 533 MHz, you had to have memory clocked at 333 MHz or 400 MHz.
If a processor has a FSB of 400 MHz had to have memory clocked at 266 MHz or 333 MHz.
Basically the memory had to support the FSB of the processor. You could use memory with a greater capacity for the lower end processors, but not visa versa.
Now I'm getting into dual cores and core 2 processors, things seemed to have changed. When I checked on the properties of my son's system that was built by someone else, the processor is Core 2 1.6 with a FSB of 800 MHz, but the system bus is only 533.
How can that be? I thought that had to match, or at the very least the system bus was faster than the CPU bus. Am I missing the boat or have motherboard and CPU bus speeds totally been designed?
Thanks for any help you guys and gals can lend me.
ping for pc help
I’ve been out of this for years but at some level you’re dealing with asynchronous transfers and wait states to memory on the system board.
http://www.vsubhash.com/writeups/pchardware.asp
That I won't try to duplicate here...
OK, I happen to know a little bit about this subject.
The original Core-2 Duo processor, known as Conroe, has an FSB (front side bus) running at 1066 Mhz. Memory chips running synchronous with this is DDR-2 @533Mhz. I’ve seen opinions stating that the Core-2 works best with synchronous memory. However I’ve seen benchmarks where they tested 667Mhz and 800Mhz and in the real world, there’s very little difference in overall system performance. The reason is that these Core-2s have a huge L2 cache (4MB shared by both cores) so main memory is not as crucial as it is in other systems. Later Core-2s increased the FSB to 1333mhz where synchronous memory would be DDR-2 667Mhz.
The less expensive Core-2 systems,(apparently the one you have) has an FSB running at 800Mhz. So in this case, if you want memory synchronous with the FSB, you would get DDR-2 400, or DDR-2 800. The DDR-2 800 is more expensive but you would see a performance increase, probably 4-5 percent faster overall over the DDR-2 400.
This is my understanding of the technology. If anyone has corrections, please feel free to do so. This is knowledge garnered from 10 years in computer hardware engineering.
FSB (Front-Side Bus) and DIMM speed are mutually exclusive entities on a mobo. FSB is used in reference to processing power. The FSB is the data width of the channel between the processor and the rest of the board. It’s the “choke point,” of processing, if you will. The Xeon series of processors by Intel are beginning to get into quad-core technology pretty heavily with 1333+ MHz bus lanes, but the current 800 MHz buses in much of HP’s ProLiant line are pretty quick.
With the Intel Nehalem (sp?) processor line coming out in Q4 of this year, we’ll see the elimination of the FSB for what I’ve read to be a fully integrated bus system on the main board with 32 - 96 GT/s. (GigaTransfers). If this modality bears fruit, we’ll see a pretty significant change in processing in future systems.
As far as DIMM speed, that number is also representative of the data width available to the RAM modules for processing across the bus. I believe that the two speeds utilizing the same multiplier on the mainboard makes them more efficient, but I’m pretty sure there’s no reason for them to be relative to one another. It was just that way prior to newer technologies coming out.
The buses can only run at the speed limit, like the rest of the traffic.
Open the pod bay doors, HAL.
I’m running AMD so FSB doesn’t have much meaing to me...Buses run faster with the AM2+.....lets the Phenom Quad really perform....
The buses can only run at the speed limit, like the rest of the traffic.
Unless there is a Nagin in New Awelins.
“Unless there is a Nagin in New Awelins.”
Those buses were privately owned and contracted out by the school board. The comapany that owned them left them to flood, not Nagin. Nagin couldn’t use them unless he stole them.
One kid did take one, loaded it with refugees, drove it to Texas, and was a hero for doing the right thing.
However, I'm going to be getting a 3.0 GHz dual core, not a Core 2, for this system, at least for the time being. Since there are many programs that still don't work on a 64-bit system (Nero problems big time), I will have it dual-booted between XP 32-bit and XP 64-bit.
This way, if he has to use the 32-bit boot up he won't loose much as much in the way of processing speed is if he has to run on a 1.6 GHz core 2 on a 32-bit OS.
I look forward to the day when everything will work on a 64-bit OS but right now they don't.
And thanks!
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