CPU mhz vs DDR mhz

No.7 · 26th Apr 2006, 06:53 PM

Hello.

I have a question regarding overclocking in regards to Cpu mhz and DDR mhz.

I have Asus A8n32sli nforce 4 mobo and an athlon 64 3500+ (2.2ghz) cpu together with 2*1gb corsair 3200 cas2 memory.

Now, when overclocking CPU i can reach stable 2.75ghz with e.g 250*11. (Max cpu fsb that I can run stable is 330mhz.)

Doing this with DDR mem set to auto puts the DDR memory to run 100mhz instead of 200mhz as they are SPD'd to.

Setting CPU to auto and overclocking memory I can easily reach a stable 233mhz with cas3 and also boots to windows in 250mhz but not stable. (Asus mobo set mhz in intervals, ...200, 216, 233, 250)

So, in theory I would like to run cpu at 2.75ghz and memory at 233mhz.

But this fails, completely.

When overclocking both parts, I can never go above 222mhz with the cpu while keeping the memory at 216 or 233.

Why can I not go higher with CPU fsb?

What is the limiting factor and what can I do to try and tweak myself higher?

My max multiplier is 11 on the CPU and I would like to run at 2.75ghz or as close to it as possible while keeping the memory at at least 200mhz.

The best compromise I have right now is running the cpu at 222mhz*11 and memory at 233mhz.

Br,
7

Papercut · 26th Apr 2006, 08:36 PM

I would suggest...lower your multiplier to 10x, set the HTT to 275, and RAM frequency to 166MHz (DDR333). That way you'll end up with a CPU clock of 2.75GHz and your RAM at 229MHz (as calculated by a little program called A64memfreq)

Edit: Hope I read your situation correctly

ChampionLLY · 27th Apr 2006, 12:35 AM

read a lot of articles before, most of them seems to point out that a 1:1 FSB:RAM ratio yields the overall best performance...

Chai · 27th Apr 2006, 12:42 AM

Quote:

Originally Posted by ChampionLLY

read a lot of articles before, most of them seems to point out that a 1:1 FSB:RAM ratio yields the overall best performance...

Doens't really apply to A64.

Papercut · 27th Apr 2006, 01:47 AM

Quote:

Originally Posted by ChampionLLY

read a lot of articles before, most of them seems to point out that a 1:1 FSB:RAM ratio yields the overall best performance...

Not necessarily, especially if you are compromising on latencies to achieve 1:1. Give you an example...Samsung UCCC vs Winbond BH5 (RAM capacity aside). You may be able to get the UCCC to run 1:1 with your A64 at maybe 280-290HTT, but with 3-4-4-8 timings. Take the BH5, put in a lower divider to get it running at 230-240MHz 2-2-2-5, I guarantee you the BH5 settings will give you better performance in almost any real-world setting.

And as Chai mentioned, A64 does not suffer a performance hit when running asynchronously with the RAM unlike Athlon XP, etc.

I also have read evidence to show that the difference in performance between high frequency RAM and standard PC3200 isn't that great

http://www.madshrimps.be/?action=get...&articID=3 25
http://www.legionhardware.com/document.php?id=486
http://www.techspot.com/reviews/hard...ct/index.shtml

Sure, Sandra shows bigger bandwidth numbers but in the end it's only like 2-5% extra frame rates in games

That's why I could never justify spending too much on RAM (Value VX *cough* )and I don't particularly recommend it to others either. And when helping people with their overclocks I always tell them to drop the RAM frequency if they haven't already...there's no point keeping the RAM speed as high as possible if it's stopping you from getting 500MHz more out of your CPU.

Damn, that turned out to be a long post.

werty316 · 27th Apr 2006, 02:38 AM

Yep that is true not having a 1:1 OC in a A64 rig makes no difference. Don't worry about it just keep your memory at 200MHz (400MHz effective) and over and you will be fine. You could also trying increasing the CPU voltage if you haven't done so.

PsYkHoTiK · 27th Apr 2006, 02:49 AM

Yup. My TCCDs at 300MHz 1:1 2.5-3-3-7 is slightly slower than my UTTs at 260MHz 2-2-2-6... :mgreen: * both on 1:1 divider (1s on superpi 1mb and 1m on 32m)

But I am bridging that gap. One thing that I do see is that theres more bandwith.

Slightly higher latencies (timings duh

) but better read and write in everest (note: its a synthetic test)

ZuePhok · 27th Apr 2006, 05:29 AM

ah, just forget about OC-ing the ram No.7

you get negligible performance increase.

stick with DDR400 + the tighest timing possible, and spend the rest on other components (sound card, graphics, storage capacity, booze..ahhh whatever)

ChampionLLY · 27th Apr 2006, 01:26 PM

hmmm, thanks for the info..
never went into such details...
(i don't own a desktop PC)

ZuePhok · 27th Apr 2006, 06:14 PM

Quote:

Originally Posted by ChampionLLY

hmmm, thanks for the info..
never went into such details...
(i don't own a desktop PC)

you mean you own an apple? or what?

26th Apr 2006, 06:53 PM	#1 (permalink)
No.7 Newbie Join Date: 25 Apr 2006 Posts: 5 Reputation: 0 Rep Power: 0	CPU mhz vs DDR mhz Hello. I have a question regarding overclocking in regards to Cpu mhz and DDR mhz. I have Asus A8n32sli nforce 4 mobo and an athlon 64 3500+ (2.2ghz) cpu together with 21gb corsair 3200 cas2 memory. Now, when overclocking CPU i can reach stable 2.75ghz with e.g 25011. (Max cpu fsb that I can run stable is 330mhz.) Doing this with DDR mem set to auto puts the DDR memory to run 100mhz instead of 200mhz as they are SPD'd to. Setting CPU to auto and overclocking memory I can easily reach a stable 233mhz with cas3 and also boots to windows in 250mhz but not stable. (Asus mobo set mhz in intervals, ...200, 216, 233, 250) So, in theory I would like to run cpu at 2.75ghz and memory at 233mhz. But this fails, completely. When overclocking both parts, I can never go above 222mhz with the cpu while keeping the memory at 216 or 233. Why can I not go higher with CPU fsb? What is the limiting factor and what can I do to try and tweak myself higher? My max multiplier is 11 on the CPU and I would like to run at 2.75ghz or as close to it as possible while keeping the memory at at least 200mhz. The best compromise I have right now is running the cpu at 222mhz*11 and memory at 233mhz. Br, 7

26th Apr 2006, 08:36 PM	#2 (permalink)
Papercut Hyperactive Join Date: 14 Jul 2004 Location: Singapore! Posts: 4,990 Reputation: 2428 Rep Power: 33	I would suggest...lower your multiplier to 10x, set the HTT to 275, and RAM frequency to 166MHz (DDR333). That way you'll end up with a CPU clock of 2.75GHz and your RAM at 229MHz (as calculated by a little program called A64memfreq) Edit: Hope I read your situation correctly __________________ PC Specs "Use in a cool dry place away from direct sunlight. Keep out of reach of n00bs. Overclock within 24 hours of opening. Do not read instructions before proceeding, do not use only as directed. May cause frustration, late nights and empty wallets. If symptoms persist please consult your hardware professional." Last edited by Papercut : 26th Apr 2006 at 09:36 PM.

27th Apr 2006, 02:38 AM	#6 (permalink)
werty316 Active Join Date: 3 Mar 2005 Posts: 642 Reputation: 138 Rep Power: 5	Yep that is true not having a 1:1 OC in a A64 rig makes no difference. Don't worry about it just keep your memory at 200MHz (400MHz effective) and over and you will be fine. You could also trying increasing the CPU voltage if you haven't done so. __________________ Guns don't kill people, Chuck Norris kills people!

27th Apr 2006, 02:49 AM	#7 (permalink)
PsYkHoTiK "Little" Devil Join Date: 8 Apr 2004 Location: On the "throne" Posts: 14,320 Reputation: 4003 Rep Power: 59	Yup. My TCCDs at 300MHz 1:1 2.5-3-3-7 is slightly slower than my UTTs at 260MHz 2-2-2-6... :mgreen: * both on 1:1 divider (1s on superpi 1mb and 1m on 32m) But I am bridging that gap. One thing that I do see is that theres more bandwith. Slightly higher latencies (timings duh ) but better read and write in everest (note: its a synthetic test) __________________ Intel SLAPL 4.3GHz @ 1.35v : 2x2GB OCZ Platinum DDR2 1066 : Asus P5K Premium : WD Raptor X : G92 8800GTS 512mb 800MHz Core WIP : XFi Platinum : Silverstone OP650 : Silverstone TJ-07 : Vista Ultimate Edition : Dtek FuZion CPU : Swiftech MCW60 : MCP655 : Thermochill PA120.3 w Scythe Ultra Kaze : Tygon R3603 1/2" ID 3/4" OD CPU-Z: SLAPL : SLA9U : FX-55 : DDR 600 : VX www.techarp.com

27th Apr 2006, 05:29 AM	#8 (permalink)
ZuePhok Hold me back! I can't stop posting!!! Join Date: 16 Dec 2002 Location: Floating Island Of Mandango Posts: 8,615 Reputation: 2913 Rep Power: 43	ah, just forget about OC-ing the ram No.7 you get negligible performance increase. stick with DDR400 + the tighest timing possible, and spend the rest on other components (sound card, graphics, storage capacity, booze..ahhh whatever) __________________ my motto: poison first, think later.

27th Apr 2006, 12:35 AM	#3 (permalink)
ChampionLLY News Writer Join Date: 23 Apr 2006 Posts: 1,170 Reputation: 716 Rep Power: 11	read a lot of articles before, most of them seems to point out that a 1:1 FSB:RAM ratio yields the overall best performance...

27th Apr 2006, 01:26 PM	#9 (permalink)
ChampionLLY News Writer Join Date: 23 Apr 2006 Posts: 1,170 Reputation: 716 Rep Power: 11	hmmm, thanks for the info.. never went into such details... (i don't own a desktop PC)