CPU running slower than rated (not a power management issue)

Hi,

Looking for a little help, as I'm stumped. I've noticed my P4 530 (Prescott) has been running at 2009 MHz, rather than the 3015 MHz at which it should run (this has been checked using Everest, CPU-Z, and other diagnostic tools under OS X). I've updated the bios, reinstalled the chipset drivers, reset the bios, switched to the backup bios, and so forth. Nothing I do seems to have any impact on the CPU speed.

I've booted into OS X (10.4) and the "About this computer" dialog also lists the speed as 2GHz.

Just moments ago I took the machine apart and put it back together - everything is seated correctly and has been dusted. Having changed nothing in the bios between when it was running at 2009 MHz and now, the clock speed has dropped again - it's now running at 1.51 MHz.

CPU-Z tells me the FSB speed is only 400MHz and the multiplier 100. I've attempted to "overclock" the machine using the godawful Gigabyte tweaker, which simply resulted in hard crashes each time.

The bios MIT system doesn't let me specify anything but an arbitrary speed setting (CIA2 - cruise, turbo, full thrust, etc) and the CPU host controller rate - these settings have no impact on clock rates as far as I've seen.

SpeedStep isn't supported on this CPU, and the power management setting in XP is set to "always on".

I've searched and searched for a similar situation, but the solution for every similar problem I've seen has been "turn off SpeedStep" or somesuch.

Any thoughts would be much appreciated.

Thanks in advance,

He just said he reset the bios.

To O.P.

What model motherboard is it?

FSB looks right for 400, but the mulitplier should be 15 not 100

Wow.. OC a mac OS X?

He's right about speed step, don't see that supported for the 530:

Processors 530

Hard to say what in the bios is causing it.

Almost sounded like "hard to say what in blazes is causing it".

Edit:

I agree with Zenthar, it could be overheating and throttling down, since the OP mentions it dropped even further. Its been soo long since I've ever seen my P4 northy throttle. . o O (thing is.. it never did)

^heh... in XP there isn't an off for power options which would be power management. But the OP is runing OS X. . o O (which is stating the same thing)

Edit:

And if it is over heating (since he mentioned he cleaned it up).. it should only be a matter of time when the system shuts off, that is if the thermal trip still works.

OP - Did you take the HSF off to clean it, and re-apply the thermal grease correctly?

I wounder if his mobo is setting the multi lower than it should be. Although since he probably does not have Speedstep then his multi should always be locked at the max which is 15.

I did hear about certain mobos that may bot support the multis but that was with Intels new half multis (i.e. 9.5x).

Something is wrong if its not allowing it to stay at 15x.

Unfortunately not, as I can't get into Windows. I can tell you the same details but they won't be verfied.

For the last day I haven't even been able to boot the machine - components get power, and nothing happened.

Without changing anything at all, I tried it again today, and the machine booted at 100x15, but wouldn't find any boot devices.

A few attempts later, it booted at 133x15 (Windows bluescreens, OS X panics) - then stopped booting again.

I reassembled the machine *again* and managed to get the machine to boot from a MemTest disc at 200x15 (first time I've seen that since I noticed the initial problem).

Anyway, the machine is running tests now but I don't think it's anything that MemTest would find - just covering all bases for good measure.

Seems pretty fubar to me, but I'll run some more diagnostics with UBCD and see how it fares.

Could be the PSU. If you look at the spec's from what I linked on your 530, it should be at 1.4v.

If you have another PSU handy, give that a shot, or try to obtain one for testing.