question about FSB speeds an Intel

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KoDt

Gawd
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Feb 12, 2003
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ive always been an amd guy and havent paid attention to intel, a friend of mine recently bought a new p4 2.8e processor and he wants me to overclock it for him.

My system is as follows a epox8kha+ kt266a chipset
i have a athlon 2400+ running at 133X15 (not overclocked)
so the bus speed is 266 and fsb is 133
with pc2100 ram (ddr 266) so its running at 133, cas times (2.5, 2, 2, 5)


so p4's can run at 800mhz fsb
no ram can run at 400mhz so does the ram and cpu run at nonsynchronous speeds? b/c i noticed the fsb of some p4s at 200, then the bus speed is 800, so its getting multiplied by 4?

I told him to order pc3200 ram but i was wondering if taht was ok. (for overlcocking) Cuz i was thinking about it and 800mhz fsb jsut confused me.

Ok so correct me, tell me where im right/wrong etc..
 
thx, so what about when you run it at 533, is it running at 266x2 or 133x4 ?
 
Athlon XPs have a doubled pumped FSB (effective FSB is 2x the actual FSB), and Pentium 4s have a quad pumped FSB (actual FSB x 4).

By default, the P4s and Athlons will run at 1:1 between memory and CPU (synchronously).

For 800 Mhz FSB Intels (200 Mhz actual), PC3200 is the low limit for memory if you want 1:1 timings.

For overclocking, I'd look at PC3500 to use 1:1 up until 220 Mhz memory or so, but then you'll have to use a divider (5:4) to get the clock speed higher.

Also, if you set the FSB to 533, the memory and CPU will both run at 133 Mhz actual (CPU will be 133 x 4, memory will be 133 x 2) if in 1:1 mode, and the chip will also have a lower clock speed (because the speed is actual clock speed * multiplier).
 
yeah, what they said ~~>^

intels are quad pumped. so the fsb is always multiplied by 4. thus 533mhz would be 133x4.

Also, with intels. it's ok to run the bus speed and ram speed out of sync using the dividers. sometimes some people even get better performance that way unlike with AMD's. Just depends on your setup. Just play around until you find what works for you.

i would also recommend PC3500 at least as well.
 
thanks for the input.. also on my motherboard, if i installed pc3200 ram, would it work but just run at 2100 speeds?

in my bios i can change my fsb up to 200 from 133. my motherboard is a kt266a so im not sure how much it can take but if i had 3200 ram in there could i step it up from 133? or is this impossible
 
If you put PC3200 in there and the system's set to synchronous, then yes, the memory will be clocked at PC2100 speeds to match your CPU. And yes, having faster RAM would allow you to overclock the FSB from 133. Just how much while keeping it stable is all up to luck and the proc.
 
If you put PC3200 in there and the system's set to synchronous, then yes, the memory will be clocked at PC2100 speeds to match your CPU. And yes, having faster RAM would allow you to overclock the FSB from 133. Just how much while keeping it stable is all up to luck and the proc.
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Yes, and once you start turning your fsb up, your ram will be able to keep up with it because it's rated at DDR400 (or 200mhz). Which means even at 1:1, that PC3200 RAM can handle your mobo's fsb limit all the way up to 200, (which it probably won't go that far anyway). So you'll be golden with that ram.

Because of that, I might try using a 4:5 divider and take advantage of that fast RAM. I've tried 1:1 and 4:5 for me on my 200fsb limited board and I get better performance from the 4:5. The 1:1 lets me clock higher, but windows runs better for me on 4:5. Plus I have error in Prime with 1:1. I think the only thing holding me back is my crappy and slow ram. If I got me some DDR500 then I could really try and push my little B chip.
 
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