Hi all...
I just built a quiet (not silent) system. I have a Athlon Mobile 2400+, an ABIT NF7-S and 1 gig of Mushkin PC 3500 DDR Ram. I seem to remember from past posts on this forum, discussions regarding undervolting the CPU and overclocking the memory to achieve cooler operation while at the same time maintaining “standard” system performance. Can’t find anything using the search function.
Any help in pointing me in the right direction will be much appreciated. Thanks in advance.
Redtop
P.S. I am not having any cooling difficulties, just never been an over or under clocker and want to review before I mess with anything.
Undervolt and Overclock?
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Ralf Hutter
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I searched for "undervolt* AND cpu" and got 425 hits, many of which look like they'd be quite useful by looking at the thread title. There's a big thread dedicated solely to the mobile Bartons too. There may be some very specific info in that one.
And you shouldn't have to do anything to the memory in an undervolted system. It runs on it's own separate voltage and since you're not changing the FSB of your system, it will be running at it's normal default settings already.
And you shouldn't have to do anything to the memory in an undervolted system. It runs on it's own separate voltage and since you're not changing the FSB of your system, it will be running at it's normal default settings already.
Undervolting the CPU doesn't reduce performance at all. Everything still runs at the same speed, you're just using less power to do so. It's a easy, risk-free, win-win way to reduce heat, and thus noise.
What you're probably thinking of are the discussions about adjusting the FSB and multiplier to underclock the CPU while overclocking the RAM to compensate.
An example: Say you had an XP2100 (I'll use that as an example since I happen to know the relevant stats for it) It defaults to run at 1.6 volts, with a FSB of 133 and a Multiplier of 13. That gives the CPU a total clock of 1733Mhz (13 x 133) and a heat output of 62.1 watts.
But you could underclock the CPU by reducing the multiplier to say 10, and upping the FSB to 166. That would reduce your CPU speed to 1660Mhz, but the increase in FSB would make up for the loss in clock cycles. The change alone would drop your heat output by 5%. Plus, now that your CPU is running at a lower speed you'll be able to undervolt it more. Dropping the vcore 0.25 on our hypothetical 2100+ to 1.35 would get you a reduction of better than 30% in its heat output.
There is no magic formula for how much you have to up FSB to balance out the performance loss of the CPU speed. It'll be a trial and error game to see what your system will handle, and whether the performance loss will even be perceptible to you.
Doing a search here for undervolting will net you a big bunch of threads on the topic, the Reader's Digest version being: go down one step at a time, and check for instability at each step with Prime95.
Do a search here for the 8rdavcore program...that works with your mobo as well, and may be of interest to you.
What you're probably thinking of are the discussions about adjusting the FSB and multiplier to underclock the CPU while overclocking the RAM to compensate.
An example: Say you had an XP2100 (I'll use that as an example since I happen to know the relevant stats for it) It defaults to run at 1.6 volts, with a FSB of 133 and a Multiplier of 13. That gives the CPU a total clock of 1733Mhz (13 x 133) and a heat output of 62.1 watts.
But you could underclock the CPU by reducing the multiplier to say 10, and upping the FSB to 166. That would reduce your CPU speed to 1660Mhz, but the increase in FSB would make up for the loss in clock cycles. The change alone would drop your heat output by 5%. Plus, now that your CPU is running at a lower speed you'll be able to undervolt it more. Dropping the vcore 0.25 on our hypothetical 2100+ to 1.35 would get you a reduction of better than 30% in its heat output.
There is no magic formula for how much you have to up FSB to balance out the performance loss of the CPU speed. It'll be a trial and error game to see what your system will handle, and whether the performance loss will even be perceptible to you.
Doing a search here for undervolting will net you a big bunch of threads on the topic, the Reader's Digest version being: go down one step at a time, and check for instability at each step with Prime95.
Do a search here for the 8rdavcore program...that works with your mobo as well, and may be of interest to you.
Thanks Ralf and Rusty,
I saw all of the undervolt threads, but my search parameters were not as good as yours. Where I was confused (and thanks for clearing my mind) was the relationship of undervolting to FSB. NONE! The explanantion of underclocking and boosting the FSB were the 2 factors I was after.
Also thanks for the heads-up on 8rdavcore. will look into this.
I saw all of the undervolt threads, but my search parameters were not as good as yours. Where I was confused (and thanks for clearing my mind) was the relationship of undervolting to FSB. NONE! The explanantion of underclocking and boosting the FSB were the 2 factors I was after.
Also thanks for the heads-up on 8rdavcore. will look into this.