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533mhz bus speed CPU and ddr400 ram = pointless??

Last response: in CPUs
February 6, 2003 1:46:45 PM

Is it pointless to use DDR400 ram with a 533 mhz bus speed CPU? Because from what I read, the CPU wouldn't support this ram anyway. But the benchmarks I see for the Sis655 boards do show higher performance with DDR400 ram.

Heck, I'm not even sure if the CHIPSET supports DDR400 ram. It shouldn't, but the Gigabyte board says it does. So, if it is pointless to use DDR400 ram with a 533mhz system bus speed CPU, the what would be the point of having a 533mhz fsb motherboard support DDR400 ram???
February 6, 2003 2:22:29 PM

PC 3200 CAS form corair cost the same as PC 4200 so it become useless to buy PC3200

1 the standart on DDR 400 will be change soon
2 non official support from SIS for PC 3200
3 high price on Dual DDR
4 RDRAM will be able to be use with R659 with support of prescott and Quad channel RDRAM.
5 proven platform
6 hihger performance and good overclocking
7 low capacity compare to DDR thank to I850.

Compare to Pc2700 thing change a bit

Just next to the lab and the bunker you will find the marketing departement.
February 6, 2003 5:15:17 PM

Thanks Juin for replying to all my posts here as well as on the CPU board, but it is unfortunate because I don't really understand what it is you're saying in any of the replies. I understand this is international board so perhaps your native language isn't English. But if someone else knows what is recommended or has their own thoughts please let me know.
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February 6, 2003 5:29:57 PM

Yes but what does he mean?
Buy Rambus instead? I'm sure its a great answer but not sure what he's saying.
February 6, 2003 8:37:40 PM

STill not sure anyone can answer me on this point though, abstracting from Rambus etc. etc., I know various AMD dual DDR platforms officially support DDR 400 ram, but for a p4 based system, they say the P4 can't support DDR400 ram now, so even if the mobo supports it the performance won't go up. But they also have benchmarks showing that a p4 system on the beta sis655 boards perform better with p4 DDR400 ram over DDR333!

And the Sis655 chipset claims only to support DDR333 anyway but the Gigabyte board says DDR400 is supported so what's the darn deal?
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February 6, 2003 11:27:49 PM

There is no such thing as CPU support for any given memory, it's all in the chipset. Going back to the SiS 648 as an example, it was DESIGNED to run DDR400, but a few board manufacturers had trouble getting their boards to support it, so SiS backed down and said it only supports DDR333, even though it still supports DDR400. Gigabyte was the only company to offer good, solid support for DDR400 on the SiS 648, with their 8SG667 board (later revised as the 8SG800).

Now comes the SiS 655. It's a little faster than the 648 due to dual channel DDR SDRAM. BUT SiS is familiar with companies such as Asus having problems making the board support DDR400 while maintaining their usual low standards, er, low manufacturing cost. So even though the 655 is also designed for DDR400, you won't hear that from SiS. Gigabyte still follows their own standard of excellence "if they want a better quality board that supports DDR400, and it cost $3 more to make it, do it, and pass the cost on to them". Great plan for high end users who are willing to pay the extra cost for a quality product.

The 8SQ800 series (under various names now) is their DDR400 supporting SiS 655 board. Notice the "Q" as opposed to the "G".
