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Bar81

Does Overclocking A Cpu Create More Heat Even If..

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Just a wondering if I take my 2.8C P4 and overclock it but don't change the default voltage, it should still generate more heat because it's working at a higher clock speed, correct? If so, any rough ideas of heat increase? The reason I ask is that I'm considering getting some good ram and overclocking but heat is an issue so I wanted to be sure I'm not wasting my time.

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I know that it will, I don't know how much.

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you shouldn't need 'good' ram to overclock a p4; any normal stuff should do fine as long as it's stable already. you can overclock the cpu and still keep the memory sane.

as for ocs w/o voltage bumps, GOOD ones are not common, and it will raise the temps. the % depends on the oc, the luck of your chip, room temp, case cooling, etc.

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TO quite good approximation, the CPU power will increase as a linear function of the relative clock frequency and as the square of the relative voltage.

Examples.

1. Increase clock speed (alone) by 10% -> Power increases by 10%

2. Increase Core volts (alone) by 10% -> Power increaces by approx 21% (1.1*1.1).

3. Increase both Clock and Volts by 10% -> Power increases by approx 33% (1.1*1.1*1.1)

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CPU circuits power can be simplified and represented as a simple resistor in a circuit. Many factors will effect the overall behaviour but the following generalisation will be a good guide. You can work out the increase factor (assume P = 1) or estimate power consumption if you know a idle/max power rating of the CPU.

The simple answer is:

* If you change the voltage but same clock speed, same CPU, power goes up exponentially (P=(V^2)/R).

Eg. If 60w@1.5V then ~68.3w@1.6V.

Pnew = Pold * (Vnew^2/Vold^2)

* If clock speed is change with all else being equal, power is linear.

Eg. If 60w@2GHz then 72w@2.4GHz

Pnew = Pold * (Cnew / Cold)

* If voltage and clock speed changed, apply both of the above.

Eg. Voltage increased (1.5v to 1.6v) = 68.3w; then multiply by 1.2 for the 20% clock rate increase for a final figure of ~82w.

PS: '^2' means 'the square of' or 'to the power of'.

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Actually I have overclocked my AMD Barton 2600+ to 2800+ and not one bit of difference with heat.  Using stock HSF.  39C Idle.

idle temperatures do not matter.. load is the important setting and if you run at a higher speed it will get hotter. Why? Because most of the thermal loss occurs when gates in the chip switch from one position to another, the junction capacitance requires a large current flow to change states. If you change states more quickly, or more times/ second, you will create more thermal energy and consume more power, even if the voltage is the same.

In 'idle', I would assume that most chips try to minimize the thermal loss.

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Thanks for the info guys especially the numbers. I just tried pushing my PC3200 to 220FSB. WHile it failed in about 15 minutes (as expected, it's CAS3) I was able to see the temps under full Prime95 load which were only about 2-3degrees higher than at 200FSB (2.8C CPU). Now off to get 2x512MB Mushkin Level II Black and see if I can't get 215-200FSB at 2-2-2-6 :) but DAMN that memory is expensive - close to 2x what I have now but the performance as well as overclocking improvement will be worth it.

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BTW, the linear relationship between heat and clock speed is only for CMOS fabricated circuits. Other types of fabrication operate differently.

I also beleive that as we continue to increase leakage (by reducing the feature size), the level of static power dissipation will go up more significantly. Loosely translated, as the transistors get smaller, they leak more electricity. :)

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Without wishing to to swamp this thread with technical details, we shouldn't forget that while reducing feature size alone increases leakage, other technolgies are being implemented in parallel with process shrinks to reduce/limit the increase in leakage.

I believe SOI and low K dielectrics both reduce the leakage, but the point is, a process shrink doesn't necessarily imply an increase in leakage if other process technologies are introduced at the same time.

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The money for the expensive memory is worth it, errr to you maybe but you could buy a lot of other things that would probably increase performance better ;)

And I should hope you can get 215-200FSB out of it ;)

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but DAMN that memory is expensive - close to 2x what I have now but the performance as well as overclocking improvement will be worth it.

no, it isn't worth it. expect to see 1-3% better performance on average for double the performance. this money would almost assurably be better appropriated to video, storage, memory, or cpu.

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Okay, I'm game. Only concerns are noise and heat - I won't increase the first and want to minimize any increase in the second. Here's what I have right now:

P4 2.8C w/Alpha PAL8945 + 80mm Papst 1500 rpm fan

2x512MB Kingston PC3200 CAS3

Asus P4S800D-E Deluxe

Chieftec case w/Acoustipac v2; 1 case fan 80mm Papst 1500rpm exhaust

Radeon 9700 Pro Ultimate (no fan)

Aureal Vortex 2 rev.b

Intel Pro/100 S NIC

WD Raptor WD740G HD

2x7200.7 120G SATA (RAID1) w/Zalman Heatpipe coolers

Plextor PX-708A DVD Burner

Philips 17" Widescreen LCD

The RAM upgrade will cost me about $150. How could I better improve my system for that amount than overclock my CPU and have RAM of the fastest timings (and from my understanding without a voltage mod those aggressive 2-2-2-6 1T timings will max out at 220ish FSB)?

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but DAMN that memory is expensive - close to 2x what I have now but the performance as well as overclocking improvement will be worth it.

no, it isn't worth it. expect to see 1-3% better performance on average for double the performance. this money would almost assurably be better appropriated to video, storage, memory, or cpu.

From what I've seen going from CAS3 to CAS2 ultra aggressive timings should yield a 10FPS performance improvement even at 1024x768 per the Toms Hardware Guide article. Also, increasing the FSB and overclocking the CPU to 3+ should improve performance also and more so in conjunction with the FSB increase. If I'm reading something wrong please lmk.

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virtually everything at thg is a joke, so it could be safe to consider everything you see there 'read wrong'.

10fps gain. compared to...what? was it 10fps before? 100fps? 300? the only thing you need to consider is the percentage gain over standard memory. i can assure you that in typical applications and games, it is in the very low single digits. that same money can buy a better video card.

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Well, okay, given the system and requirements I've given above I would still think that a RAM upgrade and moderate OC would best improve performance. What RAM upgrade would allow me to OC to 215-220 FSB and what Video Card would allow me to improve performance for about $150ish. Assume sales value of RAM and VC is $350 for the sake of discussion.

As for the aggressive timings it tops out at around 6-7% from what I can tell and is typically in the 3-4% range.

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if you're running a 215-220fsb you're going to have to run at 1:1 (ddr430 or ddr440), otherwise you're underclocking your memory. 250fsb is very achievable on many p4s including the 2.8c. if you do that, you can run 5:4 with perfect ddr400. cheap buffalo pc3700 from newegg should handle any of those speeds, but will probably not do it with aggressive timings unless you get lucky and/or seriously crank the ddr voltage.

glancing at your specs i would probably spend the saved money on a bigger monitor if i had to spend it.

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Remember the heat. At 250 FSB given my current heat box of a case and my low rpm fan solution the 2.8C would be well above 60C under load which is unacceptable. Thus, the moderate overclock is what I want and you're correct, I need RAM that runs 1:1 and I'd prefer some good RAM such as Corsair, Mushkin, Kingston, etc with a decent warranty

Monitor wise I'm very happy with what I have and I doubt I could get a better widescreen lcd for even $150 - but that still doesn't address performance improvement.

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So, basically you're saying find the cheapest RAM that lets me overclock to FSB 215-220 at any timings, correct? Would the Corsair XMS line allow me to do that?

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As for the aggressive timings it tops out at around 6-7% from what I can tell and is typically in the 3-4% range.

Yep. 3-4% for certain games.

Of course, you are now losing 3-4% in most other applications (based on same tests).

(That assumes a change in memory fequency ...)

I'm using blue Kingston memory. It's the HyperX line (PC3200), but I bought it because it was blue -- why else would I waste money by not buying Crucial? ;)

Really though, I found it on sale - and it did really well with my mild overclocking.

In a Shuttle SB75G2:

2.8GHz @ 3.2GHz (230MHz FSB) (maybe 228)

PC3200 @ 1:1

Raised voltages on both components.

You guys with your giant PCs and all those fans. . . B)

From the "For What It's Worth" department,

Dogeared

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any ddr433-rated memory or higher, and most decent ddr400 would do it. buffalo has a lifetime warranty as well. if you still want the more expensive stuff, by all means buy it. i just felt i should point out the 100% price increase in exchange for a 3% system increase.

since you seem to be focused on games, why are you buying a WIDESCREEN LCD? freaky resolutions don't look good scaled, and even 16ms lcds (i don't believe yours is one) are not sufficient for serious fps play.

the dell 2001fp might still be $750. 20", 16ms, 24bit. how much is the one you're buying?

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Okay, I like my widescreen because it gives me more desktop space, I can rotate it while websurfing, allows me to rotate it for my SS TATE mode and feels like the arcade. I'm partial to it and frankly, the scaling in games doesn't bother me - I don't see a huge visual issue there, but that's just me.

Okay, thanks for all the advice, I think maybe I was paying way too much for RAM, I'm thinking the best course of action right now would be some PC3500 (215) at decent timings for between 85-105 per 512MB stick. Selling my old sticks the upgrade should be very reasonable and the best thing I could do right now, I would think.

I do care about games btw, but my system is more geared towards quiet operation with max performance for multiple applications. Otherwise I'd get at 875 board, a 2.4C, some ridiculously loud fans and go nuts :)

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i would try pushing your 3200 to see how far they'll go first; if they're decent chips (like winbond bh-*) they could very well do ddr433 with decent timings if you feed them enough voltage (no mod). anything to save you from the ebay process :)

i use 2x512mb kingston hyper-x pc3500 in my system (very good deal at best buy).

have fun with your system.

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