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Ram increases freq when i increase cpu freq - Page 2

post #11 of 16
Quote:
Originally Posted by rhcpcrony View Post
(using DDR2 800)
If he sets the FSB from 266mhz to 350mhz and his ratio is 1:1 that would lower his DRAM from 400mhz to 350mhz? Would setting the ratio to 1:2 or other on the bios be the same as having a 1:1?

Obviously having FSB to 266 and DRAM run at stock 400mhz is literally useless since having greater DRAM than FSB offers no performance boost?

This is probably where dividers and multipliers come useful, but what if the multiplier is locked or something...
A ratio of 1:1 at 266Mhz QDR FSB (1066 rated) = 266 DDR ram (PC4200 or often called 533 ram)
if the FSB is raised to 350Mhz QDR (1400 rated) then the ram would run at 350Mhz (700 as people call it) still under PC6400.

To run the ram at PC6400 speed with a 1:1 ratio the FSB need to be 400Mhz QDR (1600).

Someone who run his FSB at stock (266Mhz QDR 1066) and his ram at PC6400 is not running at 1:1 from the start. Thats a 3:2 ratio because:

266.67 x 3 = 800
400 x 2 = 800

Most Core 2 CPU's reach 400FSB (1600) without much work in those cases PC6400 ram at 1:1 in dual channel is all that is needed to fill the bandwidth of the FSB anyway.

400mhz FSB x 64 (bit wide) x 4 (Quad data rate) / 8 (bit to byte conversion) / 1024 9Mega to Giga conversion) = 12.5GB/Sec
400Mhz Memory x 64 (bit wide) x 2 (Double data rate) x 2 (Dual Chanel) / 8 (bit to byte conversion) / 1024 9Mega to Giga conversion) = 12.5GB/Sec

The same is true at stock speed:

266mhz FSB x 64 (bit wide) x 4 (Quad data rate) / 8 (bit to byte conversion) / 1024 9Mega to Giga conversion) = 8.31GB/Sec
266Mhz Memory x 64 (bit wide) x 2 (Double data rate) x 2 (Dual Chanel) / 8 (bit to byte conversion) / 1024 9Mega to Giga conversion) = 8.31GB/Sec

So there is no need to run the ram at PC6400 if someone run his CPU at stock 1066 bus without overclock. All the gain with faster ram than FSB is due to shorter cycles and can be gained with lower timmings at lower frequency since raising the memory speed needlessly also make tighter timmings harder to reach.
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Cerebro
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post #12 of 16
Much confusion here? Are you talking about rated or actual frequency of RAM?
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post #13 of 16
Thread Starter 


That is what CPU-Z says so far. Since i can't adjust my ram speed except for auto/667/800/1066, does that mean i won't be able to get 3Ghz?
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post #14 of 16
I think 3 Ghz is like almost 70% increase. Thats too much. Correct me if I am wrong.
My System
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Northwood P4 2.4Ghz Asus P4PE Geforce 4 - 64 MB 1G (2 x 512 MB) 
OS
Windows XP SP2 
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My System
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Northwood P4 2.4Ghz Asus P4PE Geforce 4 - 64 MB 1G (2 x 512 MB) 
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post #15 of 16
put your ram on the lowest, right after auto. then put your fsb on 333mhz multi 9, then you have 3ghz
post #16 of 16
Thread Starter 
I got 3060mhz with vcore 1.392 but that changes to 1.376 frequently then back. Does that seem low or high or bad?
Actually, i just got a rapid lockup,bsod,then restart. now i set my vcore to 1.408
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My New Build
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CPUMotherboardGraphicsRAM
E4300 BIOSTAR TForce TP35D2-A7 eVGA 8800gts CORSAIR XMS2 2GB DDR2 800MHz 
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