Worth the trade off?

S

Skychan

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Dec 25, 2005
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Ok, i've read quite abit about OCing, so i dont need any basics, i just want to understand one thing.

First my system: 4400+ on evga SLI mATX mobo (Nvidia NFORCE4) with OCZ platinum DDR400.

In order to OC this CPU a great deal higher than its stock speed, i must reduce the HyperTransport freq to something like 600mhz and the memory freq to 166mhz or maybe lower.

Seems to me this is quite the trade off and I want to understand if it really is worth it to get higher CPU speed but sacrifice overall system performance like the HTF and memory.

...or will the HTF and mem speeds be affected and increased when increasing the CPU bus frequency? Somehow i highly doubt that since you are FIXING their speed... but then why can't you just FIX them at 1000 and 200?

Thanks for any insight!!!!
 
The Hypertransport link speed really won't be an issue, and it will clock back up as you increat the FSB. (I know it's not really called the FSB on AMD, but to save from confusion...)

The Hypertransport link and the memory speed will increase with the FSB. The speed you set for the memory in the BIOS (IE: DDR 333) basically changes the ratio of frontside bus speed to memory speed. I don't know what the various ratios are, sorry about that. Anyways, example: from 1:1 to 5:4. So if you have a 5:4 ratio, if you increase the FSB speed by five, you will increase the memory speed by four. So a 200 mhz FSB would result in 160 mhz memory. To get back to spec on the DDR you would have to increas the FSB by 50 mhz, which would give you a pretty good overclock. Anyways, hopefully that explains it.
 
Great explanation above.

My ram doesn't OC too well, so I chose to not mess with overclocking it so with my settings I am essentially running HTT and Ram stock while overclocking the cpu.

HTT set at 4x(800).
Ram set to DDR333
CPU set with a 10.5 multiplier

A FSB of 249 gets me...
a X2 4200+ @ 2590
HTT very close to full speed and Ram also close to stock DDR 400 speeds.

I could have went higher and pushed the Ram a little, but my rig is meant to be quiet so cpu cooling is an issue going higher than this.
 
thx a TON you guys! that makes perfect sense, i understand that now.

what might the command rate (of 1T vs 2T) have to play in OCing? (from other threads i gather that i will have to set it to 2T.. so how much of a performance loss am i looking at for ram based on that?)

And... what about memory timings? should i increase those or leave as stock and just decrease the memory speed (DDR333)?

thx!
 
1T is... faster (not in any real life stuff, really, mostly in benchmarks) but usually less stable.

My board refuses to post in 2T so I'm stuck at 1T (too bad for me eh ;) ). So If you're stable at 1T, use it... If not don't. There wont be much of a performance difference.
 
This is where a lot of experimenting comes in to play. If it gives you any idea, I'm still tinkering with timings vs. mem clock on my machine.

Dual-Cores really crave memory bandwidth, so in my oppinion it would be more to your benefit to raise the memory clock speed than to tighten (lower) the timings. For now stick with the stock timings, see how high you can get the memory clock to go like that. Once you hit the max, loosten up (increase) timings, and see how high you can get it like that. After that, you play with the ratios. When you hit the roof on your CPU, and you can't raise the ram ratio anymore (can't raise FSB without CPU instability, and increasing ram speed by changing ratio is too big of a jump), then you tighten up the timings as much as possible, and boom, you've found the sweet spot. I wouldn't worry about the command rate, just set it at 2T, you won't ever notice a real-world difference.

EDIT-
I entirely left out voltage settings, I read your other post. I felt like telling you a bit more about the timings, though
-EDIT
 
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