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[johnny9562001]

Hi i need help ovecloking my computer. I have a p4m800pro-m v2 and a intel
pentium d 805 mobo. I read that this combo has a ration of 20 making it possibel to overclock up to 4.0ghz. But dont know exactly how to overclock except for the limit that the bios gives me, which is 300mhz only. I heard i have to change the fsb, but how? any help.

[elprawn]

Go into your bios (del on startup usually) and make sure your FSB settings are on manual and just increment it little by little, restarting your computer each time, until CPU intensive software starts to crash (try benchmarking software such as Sandra and have it loop 99 times), then put it on the previous stable setting. Keep an eye on CPU temp.

Edit: If your bios has a limit of 300MHz and your CPU multiplier has a ratio of 20 then 20*300 = 6GHz.

[jmr]

i have a D805 & it has been sitting @3500mhz (FSB 175) for 2 year now with the standard heatsink with no problems
to go higher than 3500mhz you will probably have to start raising the voltage which will create a lot of heat



Pentium D805
Asus P5RD1-VM
2x512mb pc3200

[Altor]

FSB is a number that is multiplied to get your final CPU speed.

I think the mobo you mentioned is an Asus model, and Asus handles overclocking well, as does the Pentium D 805 (which I also have btw).

Overclock by increasing your FSB in increments of 3 or so.  I'm guessing you start at 133 FSB?  Or 200... er.... it's been a while since I actually looked at it.  Whatever the number is, with an 805 you can safely increase it by about 1.25x.  So if it's 150, you can probably increase it to 187.  I wouldn't recommend pushing the limit though, I'd say if you can do 187, do 175.  So like a 20% overclock...

You'll find a PCI Bus Frequency setting somewhere in your bios as well.  Set it to 66.6 or whatever the default setting is.  I think 66.67... or something...

The FSB, or Front Side Bus, is like the gear that your computer's in.  The CPU multiplier is the second set of gears.  Like on a bicycle.  You've got 20 gears at the pedals, and 300 gears on the rear wheel.  Forming combinations, you can get approximately the same performance by increasing one by a percentage and decreasing the other by a percentage.  There are limits of course.  I'm just saying that for educational purposes.  For instance, the 805 chip you have is hard-set to 20x multiplier.  So it's out of the equation entirely.  So what you CAN modify is the Front Side Bus.  However the FSB controls basically the speed of EVERY component in your computer.  It's like increasing the tempo on a record player.  But certain components (like the PCI bus) don't work properly if they're set too high, so you want to set them to a safe locked setting.

CPU voltage, don't touch it unless you're very confident.  Easiest way to kill your computer.  I'm telling you this next part just so you know, but I don't recommend trying it.  In the event that you cannot overclock your FSB any further, it is one of a few different things causing the problem.  The two most likely are that your memory (RAM) cannot handle the speed, or that your CPU cannot handle the speed.  It's like when you're in first gear with your pedal to the floor.  Push the pedal as hard as you want, you're only going to get to a certain speed.  Increasing the voltage is like going into second gear.  You now have a new set of possible limits.  The stock Pentium D 805 voltage is between 1.2 and 1.4 volts.  1.4 is the top end.  Do not exceed it.  Below 1.2 volts and it will likely not work either.  The sweet spot is about 1.25 volts and this is probably how your computer is running right now.  You can safely increase it to about 1.325 or so with zero real risk.  The other possible limit might be the memory, and it has the same problem as the CPU - it's in too low of a gear.  Depending on your motherboard you may or may not be able to adjust your RAM voltage.  Standard DDR2 ram (which you almost certainly have) has a stock voltage of about ... I forget  But you can typically increase voltage by about 0.1 v with virtually no risk.  I think the stock voltage is 1.7 or 1.8 volts.  OR it could be 1.5.  Seriously I don't remember, maybe check wikipedia for the standard specs.  But if it's, say, 1.6 volts, you can probably increase it to 1.7 with no risk.  However many brand-name memory units normally run at 1.9 volts or higher, that much I know for sure.  So if you know the brand name, check their site and they should list specs.

By increasing voltage, you also increase your power consumption.  Power comes from your power supply (also called PSU - power supply unit) and it's like the gas tank.  There's only so much gas and then you're empty.  Most computers you buy have a 300 or 400 watt PSU, this will be only adequate for very basic overclocking.  A 500 or 600 watt PSU would be safe, as long as it's a REAL 500-600 watt PSU and not just a marketing lie.  The rule is, do not buy a PSU unless it's at least $70 USD or s.  Below $50 USD and your new PSU will probably last about 3 months and then glitch out on you and you'll need another new one... so better to buy more expensive in the first place.  Don't pay more than $120.  Buy a reputable brand name with lots of good customer feedback, try searching on tigerdirect.com/.ca or newegg.com.

ANYWAYS.  There you go.  Don't go beyond a 20% overclock unless you are very confident in both your own knowledge and the quality/workmanship of your compontents.  All rather complex and intimidating for a first-timer.  If you want to just get some "free performance", increase your FSB by 10%.  No risk, zero.  It will work, and will last as long as it would at stock speeds.  Just don't forget about locking your PCI bus speed.

edit:
ALSO BEWARE THAT A NUMBER IS NOT ALWAYS WHAT IT SEEMS.  If you see in some system information utility that your DDR2 ram is operating at 400 mhz, it is not.  It is actually running at 800 mhz.  Standard "DDR" (not ddr2) would actually be operating at 400 mhz.

Many other things are this way too.  If a number seems to be like half or a quarter of what you'd expect, that's probably normal.

Some more info on the FSB vs CPU.  You can determine your CPU's speed by comparing its multiplier (which we know is 20x) with your FSB.  So if your FSB is 200 mhz and your multiplier is 20, you are running at 4 ghz, or 4000 mhz.  The Pentium D 805 runs at 2.66 Ghz at stock, so now I can deduce what your FSB speed is!  2660 divided by 20 equals exactly 133.  So I can recommend that you increase your FSB to 146 - this is about as safe as you get, and a 10% performance boost is nothing to sneeze at.  150 is a good round number though and that's what I'd use  That would put your CPU speed up to 2.92 Ghz and 3 Ghz, respectively.  For some perspective, I have my 805 running at 3.2 Ghz, 160mhz FSB.  100% stable and a healthy 20% performance boost.

You ask me, why only 160 FSB, when I could easily go as high as 180 and still be within safe temperatures?  Well... the problem's my ram.  It's *too fast*.  I have PC2-6400 DDR2 ram (400 mhz x 2 = 800 mhz actual speed.  NO idea where "6400" came from) and at its slowest setting it's still running far faster than it should, at something like 960 mhz - absurdly fast.  To INCREASE my performance, I need SLOWER ram!  Computers are weird, huh?  

[johnny9562001]

thanks altor, i appreciate your interest and lovely explanations.

[jmr]

You ask me, why only 160 FSB, when I could easily go as high as 180 and still be within safe temperatures? Well... the problem's my ram. It's *too fast*. I have PC2-6400 DDR2 ram (400 mhz x 2 = 800 mhz actual speed. NO idea where "6400" came from) and at its slowest setting it's still running far faster than it should, at something like 960 mhz - absurdly fast. To INCREASE my performance, I need SLOWER ram! Computers are weird, huh? Smile

why dont you just use the memory dividers in your bios to adjust the speed of your memory

[Altor]

You ask me, why only 160 FSB, when I could easily go as high as 180 and still be within safe temperatures? Well... the problem's my ram. It's *too fast*. I have PC2-6400 DDR2 ram (400 mhz x 2 = 800 mhz actual speed. NO idea where "6400" came from) and at its slowest setting it's still running far faster than it should, at something like 960 mhz - absurdly fast. To INCREASE my performance, I need SLOWER ram! Computers are weird, huh? Smile

why dont you just use the memory dividers in your bios to adjust the speed of your memory

I've tried it, but there's some kind of block (as in, inhibitor/bug, not as in "chunk of program") somewhere in the bios that's messing up my memory detection/timing/OtherJargon.  It's detecting my RAM as PC2-4300, not 6400.  It's probably the fault of my CPU, to be honest, since it has such a low FSB.  If I had a Core 2 cpu that had a native 800 mhz FSB I'd probably be just fine.  I'll upgrade once quad core w/ multithreading goes below $200 or if I'm feeling like blowing a whole week's pay sometime.