Intel 925X: Exploring the Overclock Lock
by Wesley Fink on June 23, 2004 12:05 PM EST- Posted in
- CPUs
. . . or Do They?
However, further tests with the 3.6 Engineering Sample shed more light on the question.
| Asus P5AD2 (Intel 925X) - Highest Stable Overclock - 3.6 ES | |||||
| CPU | Multiplier | Voltage | Highest FSB | CPU Speed | % Overclock |
| 3.6 ES | 14 | Default | 992 (248) | 3472 | 24% |
| 3.6 ES | 15 | Default | 992 (248) | 3720 | 24% |
| 3.6 ES | 16 | Default | 992 (248) | 3968 | 24% |
| 3.6 ES | 17 | 1.425V | 952 (238) | 4046 | 19% |
| 3.6 ES | 18 | 1.425V | 896 (224) | 4032 | 12% |
While the 3.6 ES was also able to reach around 4GHz when overclocked, this represents only a 12% overclock for this chip. It is not unusual for top-of-the-line processors to achieve a more modest overclock percentage than lower clocked CPUs that probably are off the same line. The advantage here is that the ES chip allows the setting of lower multipliers to determine the maximum overclock potential of this motherboard.
We should be able to achieve the same approximate 4GHz at lower multipliers - but with higher FSB. At a 14 multiplier, 288x14 would give us about the same CPU speed as 18x224. However, we find that the highest FSB that we can achieve is the same 248 maximum we found on the 3.2GHz. In fact, whatever the multiplier, 248 was the highest FSB setting that we could achieve.
While we can't be certain whether 248 is the limit of the Asus P5AD2 motherboard or an artificial limit of the chipset, we suspect that we are dealing with chipset limitations. It appears that Asus has effectively bypassed the Intel Overclock Lock, but the design of the lock cannot be completely bypassed. Even a clever design like the Asus still seems to be overclocking limited to around 25% above rated speed.
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TrogdorJW - Wednesday, June 23, 2004 - link
Going along with my last post, look at overclocking with the newer Athlon 64 chipsets. On socket 754 with second generation chipsets, what was the maximum overclock achieved? Anandtech managed to get 248 MHz, oddly enough.[H] had this to say when using the Abit KV8 Pro: "To put it frankly, this is the first time I have ever been excited about overclocking the AMD K8 core. This is the first time we have really seen tangible results that I think are going to be within the reach of the mainstream enthusiast that wants to experiement a bit with performance gains without having to reinvent the wheel in order to get there." Note that they had to run the HyperTransport bus at 3*245 for stability.
What I'm trying to get at is that with the numerous changes to the platform, I wouldn't be at all surprised to see that initial overclocking is not able to match the mature 865PE/875P overclocking results. Perhaps we'll see some BIOS revisions that allow adjustment of the NB-to-SB bus speed, or maybe PCIe in general is causing problems with overclocking right now? As usual, this is revision 1.0 hardware we're looking at, and there are plenty of bugs left to work out.
TrogdorJW - Wednesday, June 23, 2004 - link
I think the article gives a pretty good representation of the current status, but it might be a bit too anti-Intel right now. Remember, we're dealing with a BRAND NEW chipset that has all sorts of changes. New Northbridge and Southbridge, PCIe support, DDR2 support, and a new interconnect between the NB and SB, to name a few points. So, all you AMD fanboys, answer me this: how well did the first generation Athlon 64 chipsets overclock? And they didn't even add new RAM or PCIe support; all they did was moved the system bus to HyperTransport!I'm not saying Intel is perfect and AMD blows; just giving perspective. On the Asus board, AnandTech was able to reach a 248 MHz bus speed on 16x, 15x, and 14x multipliers. As the article pointed out, either the multiplier lock still exists but has been raised to 248 instead of 220, or else the bus simply doesn't run properly right now at speeds higher than 248. Until we get more information, it's a little premature to make a final judgement. We're looking at ONE Asus motherboard right now - they didn't even have several boards to try the CPU on! There's still a very good possibility that further tweaks to the BIOS will allow more than a 248 MHz bus, but Asus is working with version 1.0 hardware right now.
Pumpkinierre - Wednesday, June 23, 2004 - link
I was wondering why those 865/S775 board like the ABIT AS8 were appearing. It could be because of Prescott's power consumption that could blow mobos but it just may be that the new mobos are real screamers (already tuned to higher bus speeds for DDR667). I mean, it seems strange that ASUS can only unlock the FSB to 248MHz. You either circumvent the lock or not. So ASUS might be playing politics as well, not raising the ire of Intel too much while being still ahead of the other mobo manufacturers as far as enthusiast appeal goes.Creig - Wednesday, June 23, 2004 - link
Intel - "Additionally, from time to time, Intel may choose to implement functionality that helps to ensure that the Intel product experience is not degraded by those who may try to run our products out of spec.""from time to time"? When HAVEN'T they attempted to suppress enthusiast overclocking?
Their so-called "Intel product experience" is simply them telling you what system you want and how you want to run it. Irregardless of what you ACTUALLY want.
What a bunch of weenies.
vedin - Wednesday, June 23, 2004 - link
Wow..Anandtech got a responce from Intel in under 24 hours..you guys are fast. ::thumbs up::Fr0zeN2 - Wednesday, June 23, 2004 - link
#17 - I've seen thermal comparisons elsewhere on a [H] link, and yes, 64's unclocked gives off about 50 and prescotts give about 80-90. My Northwood gives off 130w though, and that's not even with a wild oc.sprockkets - Wednesday, June 23, 2004 - link
Overclocking a 2.4ghz prescott to 3.6 is no accomplishment when that was a low frequency on the Northwood. Prescotts slower than 3.2ghz are in my opinion underclocked, since why would a new generation of processors have to be clocked lower than its predecessors, WAY LOWER?rjm55 - Wednesday, June 23, 2004 - link
#18 -What a load of horse manure!! You would think Intel could just say "Yes, we added a 10% OC lock" instead of that convoluted explanation that leads to the same answer.
Wesley Fink - Wednesday, June 23, 2004 - link
The article has been updated on Page 1 with Intel's Official Reply to our question of whether they have implemented a 10% overclock lock on the 915 and 925X chipsets.Intel declined to directly answer the question, but provided a statement which is quoted on Page 1.
dvinnen - Wednesday, June 23, 2004 - link
Normally I don't, but they are the only ones I see with such a comparison. Plus, they are usally a Intel favoring site, so anything that shows AMD so far ahead, I figure most be alright. Hard to skew a temperature test unless you attach the dio in some obscure place. So, AMD could be more ahead.