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HOW-TO: find max FSB / CPU Speed HOW-TO: find max FSB / CPU Speed
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HOW-TO: find max FSB / CPU Speed
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Old 25th May 2002, 18:13   #1
jmke's Avatar
Join Date: May 2002
Location: 7090/Belgium
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HOW-TO: find max FSB / CPU Speed

Ok now to see if I can help. I have just answered a vastly similar question on another thread here which I'll just paste in to save time. Not all of it is appropriate to what youd like to know, but read it thru and give the appropriate parts your attention .

Ok, spread spectrum is basically a way of decreasing the effects of EM interference by increasing transistor drive strengths on the board. Unless you live in a power station it doesnt matter . Hi drive strengths have the unfortunate consequence of lowering your capacity to fsb overclock.

I presume you mean memory speed auto detect - I beleive this just allows the bios to read the eeprom chip on your ram to find out its factory suggested timings. Doesnt matter whether its on or off.

You still havent answered my question regarding your memory voltage.

I would suggest you go about things this way.

1) - remove all non essential pci cards (lan etc) so youre just left with your gfx card plugged in.
2) - turn off usb if youre not using it, if you are turn it off for now just for testing.
3) - set your cpu multiplier to something like 8x (if its not unlocked then unlock it!
4) - set cpu voltage to 1.85v
5) - set ddr voltage to 2.7v
6) - boot into windows at your previous highest stable fsb
7) - run the sandra burn in wizard set to do 10 loops of cpu bench, cpu multimedia bench and memory bench. Should take around 11 - 12 minutes for all 10 loops.
8) - If this passes reboot and increase your fsb by 2mhz, boot into windows and test again.
9) - repeat above until you fail the burn in test (lockup).
10) - when you lock up reduce mem timings to minimum (cas 2.5, no interleave, 3/6/3 timings, 2-level queue depth, 2t command rate) and try the same fsb again. If this fails then something else is holding you back. If it doesnt fail then keep going all the way until it does or you reach 166mhz.
11) - when your done testing for fsb then go back to 133mhz and set your cpu multiplier to say 11x, then increase your fsb 1mhz at a time running the sandra loops again until it locks up. This will find your max cpu speed. When youve found your max cpu speed do the following :

Set your cpu to say 1400mhz and run a sandra memory bench (old sandra not new! - 2001TE) starting at your max stable fsb with max timings and increasing the fsb and decreasing memory timings as you have to. This will help you find out at what fsb speed you get the most memory bandwidth. Try and keep your cpu speed as close to 1400mhz as possible by adjusting the multiplier in order to keep the tests as fair as possible. Make a note of at what fsb you had to decrease timings. 4way interleave is usually stable *** the way thru, youre most likely to have to change the command rate and timings, maybe the cas rating. The most important timings in terms of bandwidth are highlighted below :


And in terms of importance :
4way interleave
command rate
the third timing (trcd?)
the first timing (trp?)
cas rating
queue depth
the second timing (tras - should always be set to 6 anyway)

Divide your max cpu speed by your best fsb to find what sort of multiplier youre aiming for. If for example your max cpu speed is 1500mhz and your best fsb is 162mhz then your best setting would be either 9 x 162 or 9.5 x 158. Test both settings to find which is fastest, again using sandra memory bench, and possibly 3dmark 2001 as well. You may well find that lower than max cpu speed and a higher fsb will be faster than highest cpu speed and lower fsb. You can also try rounding up or down to the fsb where you had to change timings, adjusting the multi as necessary. You should basically find yourself with 3 or 4 combinations to check.

Once you have found your desired FSB then add back your components one at a time testing with sandra after each one is installed to find if one of them is crapping out on you. First enable the usb, and then add in your cards in order of importance (ie sound then modem then lan).

I hope this answers your questions m8, if not post back and i'll do what I can to help you out some more.

Like I said not all is appropriate, but most of it will come in handy at some point or another . Id also like ot reiterate whats been said above - that heatsink really will not hack it, and neither will the psu. You should be looking at a minimum of a 350watt enermax psu, but youd be better off with a 400watter from the likes of macron, sparkle or antec. Heatsink wise the Alpha pal8045 is the way to go. Its fairly expensive compared to what youre using now, but its a VERY effecient sink. You have the advantage of being able to pick your fan, ie an 80mm delta for max performance and to hell with the noise, a mechatronics or ystech 80mm for a happy medium between noise and performance, or something like a papst or evercool 80mm for almost complete silence, but performance not much higher than a good 60mm heatsink/fan combo such as the sk6. Id recommend the ystech option as that will minimise your costs and save your eardrums . Of course you can get both or even rig up a 7v/12v switch (see and run the 80mm delta quiet for day to day use and balls out loud for when you get frisky .

Any more questions then post back, were all here to help .

Good luck, have fun and remember smoking is bad for the health of your PC .
jmke is offline  
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