Monster OCs - why is the P4C 2.4Ghz so good?

[shredisn@tdead]

chrisf6969 posted some suggestions to improve my 2.6Ghz @ 3.275Ghz - as his 2.4 is 50% OCed to 3.6Ghz thought I'd give it a try.

Well, had a good muck about...

• Set it at 3:2
• Put the FSB up from 252 to 260 (not a huge increase)
• Upgraded the BIOS to the new ASUS #12 for the P4P800 (was at #8)
• Gradually upped the Vcore from 1.675 right up to 1.875
• Set Vdimm from 2.75 to 2.85 (don't have any more in the BIOS, but as the mem is running well below rated shouldn't need to up this anyway)

And every time it freezes after about 2 mins. Looks like the CPU is maxed out and is stable @ 252fsb - even 255 is too much.

HOWEVER I found that it's SETI that makes it freeze - it's in my Startup group. When I killed it quickly I actually got to run some Sandra benchmarks (CPU slightly better, memory much worse as expected). Turn on SETI and it freezes which is a bummer as it's a SETI crunch box!

The CPU temp doesn't cross 42deg so that's not the prob here.

So seeing as you can get a 50% OC out of your 2.4 and [b]I can only get a stable 25% out of my 2.6[b], what gives??!!

Is there a difference between these CPUs and the rest of the line right up to 3.2Ghz, other than the multiplier?
Why do some CPUs OC better than others?
Is it simply that some plants fab them better than others?
If you can get 50% OC does this mean we'll see go-l.com and others shipping 4.6Ghz VapoChill machines???

Presumably there's a physical upper limit to the max speed of these chips and it's been hit at about 4.1Ghz on the nVentiv demo machine? http://www.nventiv.com/index.php?pageid=44

[chrisf6969]

Most people are getting anywhere between 3.0-3.6 on aircooling. If you start out with a lower chip you get a greater percentage increase.

So if you go out and buy a 3.2 you'll probably only get a 10-20% increase.

Then there's luck of the draw. Some chips clock higher than others with less volts. With P4's it seems like more volts doesnt really help unless you have extreme cooling so anything over around 1.65v is usually just wasted.

Also, I think the 2.4's were selling very rapidly b/c they were the cheapest 800Mhz FSB CPU so they are the most recently produced if you buy a brand new CPU. (b/c of turnover) & newer CPU's always overclock more b/c of refinements in the process, etc.

[sh4rk]

The reason that the chips are so good is that they are speed-binned. The intel manufacture and raw materials are so good that all of its chips would get to 3ghz+ but not everyone wants to pay £400 for a 3ghz chip. Therefore intel just lower the multiplyer and sell a chip that could get to 3ghz at 2.4ghz for a lot cheaper. This is the main reason why 2.4s are so good.

[shredisn@tdead]

It's looking that the 2.4s are becoming scarce, and where you can find them, the 2.6s are pretty must the same price. At least that's the case here in the UK, where they're both about £120 ex VAT.

Does this mean you might as well buy a 2.6 now? Or get a 2.8 for only £25 more? Getting the 2.8 doesn't guarantee a higher overclock speed, but the 2.6 will have a better relative % OC for the reasons chris points out.

[sh4rk]

It depends what ram you are running to what cpu you should get.

[sh4rk]

i.e. if you have a 2.4C, at 250FSB it is ideal for pc3200 ram and pc4000 ram. This means that your comp will be running at 3Ghz with a divider of 5 4 meaning that the ram will be running at 200FSB, or 1:1 meaning that the ram will be running at 250FSB (DRR500).

[SilentDeath]

stuff likes to be burned in, and rasing voltages like that before you need to is just a waste of time. on the 3 cpus ive overclocked doing what you have done doesnt give there full overclock, leave it a few weeks and theyll be able to go further, gradualy doing it is quicker.
same for mem and i assume every other chip.
overvolting mem aint good idea, unless its burned in and needs it for that speed, my pc2700 sticks wouldnt even boot at 2.77v untill burned in properly, one is now capable of ddr460 (mobo limit, so cant test higher) while the other is only capable of ddr410, but thats still very good for pc2700 sticks (samsung btw, the better stick is CTL wheras the other is DLT..)

have you tested stability yet? memtest86 and prime95 are best..

[chrisf6969]

Like Shark says it depends on your ram and what FSB & dram ratio you are shooting for.

But since the 2.6's are the same price, I'd get that and shoot for 3.25GHz+ at 250Mhz+ FSB and if you have DDR400 or DDR500 you can keep your am in spec by putting that ratio at 5:4 or 1:1 respectively.

[chrisf6969]

My computer only passes the Prime 95 stress test for a 24 hour loop at 3.45Ghz. (maybe higher that was the last mid way point I tested successfully before going to 3.6Ghz) 3.6 failed prime 95 but passes EVERYTHING else.

But I've found I can benchmark, play ANY game for hours and run it 24/7 with out errors at 3.6Ghz. I guess b/c nothing really stresses out a 3.6Ghz HT CPU, except a program specifically targeted at doing so.

[Richie]

Chris, is the 53oC your idle temp ??

If so, I realise that Prime95 fails the CPU at 3.6gig but what temp does it get to on there ??


I have a 2.6C myself and have just overclcked it to 3.25gig with vcore raised from 1.525 to 1.625, PC3200 memory on a 5:4 ratio and nothing else changed.... idle temp = 41oC on air cooling

No idea what it will go to. It was rock steady on 3gig with nothing else changed and only need vcore raised to get to 3.25 gig and stay steady.....

[shredisn@tdead]

Right, so buying a higher Mhz CPU doesn't guarantee a better overclock at all then. Anyone out there got monster air OCs on 2.8Ghz and up? Let us know!

Now it seems to me that the main issue then with building a stonking fast PC is the CPU. What about "extreme cooling"? I thought water cooling only gives say 10deg better temps, no? Does this really help OCing?

So if you want extreme OCs you've got to go to the expense of Prometeia or VapoChill, right? At least these things will be fairly futureproof as they probably produce new blocks when things change.

Also, why then would you spend 50% more on a top of the range MB like a MAX3 when a standard board will do the trick? Surely no board are future proof as Pescott is going to come in a different package (LGA), no?

And, if you've bought a CPU that doesn't OC at all well eg just touches 3Ghz (although presumably everything is now guaranteed to hit 3.2Gz no??!) WHAT DO YOU DO? Flog it on eBay and buy another (and cross your fingers?)!!!

[chrisf6969]

buying a 3Ghz or 3.2Ghz should get you to 3.4-3.6 and possibly higher

where buying a 2.4(or 2.6) should get you to 3.0 minimum and possibly as high at 3.3-3.6

Higher priced CPU's usually will get you slightly higher more often. But with good (high end air or water) cooling most chips get around 3.3-3.8. (depends on luck and your set up)

If you have a Vapor cooling system you want the best chip 3.2 or 3.0 b/c you need a high multipliter b/c you will probably be maxing it out to 4Ghz+ or so. And with a 2.4 or 2.6 you may hit the FSB wall at 300Mhz. Depends on what ram you have and what FSB you are shooting for to max that ram out.

Perfect overclock Richie... ram is in spec... and your system is probably 100% stable as a rock. And faster than any stock system you can buy!

Yeah, my idle temps 51-52.... the around 59 when gaming... and 65 with Prime95 running!

[shredisn@tdead]

Those fans are really giving it some! 6k & 7k RPMs must make a fair hum And its still toasty warm when at maximum load.

Now the heat/cooling aspect is something that confuses me too. My CPU is currently at 38oC fully loaded (2x SETI, HT enabled) ambient room temp is 22oC. My fans are at 2k (case exhaust?) & 2.4k RPM (Zalman 7000Cu), plus there's a pair of intake fans.

Presumably this just means that my OC isn't thermally constrained? If it was running @ 60 deg and say @ 3.1Ghz then that'd mean it's time to improve the cooling, right?

Switching to water isn't going to buy me any more, but vapor might? (not that I'm thinking of doing that to this PC)

OK - $6m question - can you get such big OCs in SFF PCs? It's about time to upgrade my wife's machine (my old dual PIII 700Mhz) and have thought about the new Soltek EQ3401M BUT only if I can wring the CPU like I do now! Otherwise it's a big old black box. Again, maybe my low load temps are luck and out of the ordinary?

[sparky191]

Generally SFF PC's have limited bios functionality for overclocking. Generally its FSB only and no voltage mods. I dunno if the newer ones allow any more than that. Heat is always a problem in SFF PC's. I have a friend running a P4 1.8@2.4 in one no problem. But thats a pretty easy overclock.

[Richie]

Originally posted by chrisf6969
And with a 2.4 or 2.6 you may hit the FSB wall at 300Mhz. Depends on what ram you have and what FSB you are shooting for to max that ram out.

Perfect overclock Richie... ram is in spec... and your system is probably 100% stable as a rock. And faster than any stock system you can buy!

Yeah, my idle temps 51-52.... the around 59 when gaming... and 65 with Prime95 running!

Cheers for the info


I am, right now, sitting on the PC I have done some fine tuning to. Its a P4 2.6C running on an Abit IC7-G MB and 512MB of OCZ PC3200 EL RAM (enhanced latency) and here's the specs in case anyone has suggestions for tweaking slightly -

CPU - Running 3.26gig @ 250FSB
vcore - 1.625 (0.1 volt above its standard setting)
Ram - 5:4 meaning it runs at its stock speed

Idle temp - 42.5oC (Winamp running as well as web browser so its pretty much idle)
Load Temp - not had chance to test but rose to 52oC after 2 hours of playing CS.... Thats the most load I have had chance to do so far


Not ran any tests on it yet so no idea how stable it is.

I havent touched RAM timings yet either. No idea if I need to TBH.



I am very happy with the temps. The CPU HS is a Zalman AlCu7000NPS which has a 92mm fan @ 1400RPM so is pretty quiet.