What's keeping me from OCing higher?

I have a feeling this isn't the right place for this kind of post, but I can't find anywhere better. Move if needed.

I can't boot my system with an FSB higher than 155. 156 barely works. At 160, Win2k doesn't notice that I have a hard drive. Quick math, what's stable: 150x18=2700. This is a 1.8GHz Northwood - 100MHz FSB default. Other relevant specs:
Asus P4B533 mobo
256MB of KingMax PC2700 - UCed to PC2100 due to mobo, but I think my FSB OC offsets that
Antec PLUS660AMG case, one intake and one exhaust fan
Vantec Stealth 420 watt PSU - 3 more fans
Stock Intel HSF - Hey, the highest I've ever seen it at is 52°C, at full load on both CPU and GPU (Sapphire Radeon 7000 - no fan). Usually it's around 47°C (98% load), with the mobo 27-30°C, whether I'm running it at the stock 100FSB or 150FSB.
Voltages:
at 1.8 - 1.500V
at 2.4 - 1.525V
at 2.7 - 1.575V
I've tried up to 1.625V at 160FSB, no luck. Memory is at default settings, 1:1 is fine at 150, neither 1:1 nor 4:3 works at 160.
AGP and PCI buses are locked at 66 and 33 MHz, respectively.

The only thing I can think of doing is putting a fan on the northbridge - but when I open the case and touch the heatsink, it's pretty cool. Not hot at all.

Is there anything I've overlooked that I should use to get a higher OC? Ultimately I'd like to see 200FSB (3.6GHz, hehehe), but I'm only really trying to get 166 (3.0GHz). The cooling is only stock, but the temperatures aren't too bad. What can I do to get that extra 16MHz/300MHz.

PS: I know 155% isn't bad at all, but I really want to meet my goal of 3GHz.

PSS: It runs OK at 155, but I usually run it at 150.

try bumping to 166 a new PCI divider should kick in and you might be able to get higher

are you sure the PCI bus is locked?
as that sounds like a PCI BUS problem to me too.
the more out of spec you run your PCI bus, the less things connected through the PCI bus work

also what stepping is that 1.8A? a C-1?
and you dont make it clear what kind of RAM you have. is it PC2100 or PC2700?

I have manually set the AGP and PCI buses to 33 and 66 in the BIOS.

The RAM is PC2700, but my motherboard doesn't support PC2700 so it's limited to PC2100 speeds, at least when not overclocked. Or something to that effect. It's PC2700, anyway.

Stepping... how do I check that? I'm running Win2k, as I mentioned before. I do know that it's Malaysian, S Code SL68Q.

BTW, there are only 2 things in the AGP and PCI slots: the Sapphire Radeon 7000 in the AGP, and a Netgear FA311 NIC in one of the PCI slots.

edit: I found this in the system information utility:
x86 Family 15 Model 2 Stepping 4 GenuineIntel ~2700 Mhz
I don't think that's the same stepping you mention, is it?

and pip, I'm going to go try that.

edit: setting the FSB to 166 did not work. I got a blank screen. I rebooted, it went into the BIOS automatically, with a message: Your Comptuer Hung due to an incorrect frequency. Please make sure your settings conform to the specifications of your CPU, DIMMs.... blahblahblah. The FSB was highlighted. So I brought it back down to 150, set the VCore back to 1.575, and the FSB:RAM ratio back to 1:1. And here I am.

BUMP...

it's nearly off the page. I need help here, people.

Edwards said:

I have manually set the AGP and PCI buses to 33 and 66 in the BIOS.

Click to expand...

AGP 66mhz and PCI 33mhz, I hope? Either way it doesn't sound like whatever you did actually worked. Non-recognition of components in most cases is a problem with the PCI bus running out of spec.

Edwards said:

The RAM is PC2700, but my motherboard doesn't support PC2700 so it's limited to PC2100 speeds, at least when not overclocked. Or something to that effect. It's PC2700, anyway.

Click to expand...

??? There's no reason your motherboard wouldn't support PC2700 if it supports PC2100. They're both DDR specs and use the same technology. PC2700 is just rated to run faster. It's like the difference between a 2.4gig P4 and a 2.8gig P4... as in, there is none, (in terms of technology).

Edwards said:

edit: I found this in the system information utility:
x86 Family 15 Model 2 Stepping 4 GenuineIntel ~2700 Mhz
I don't think that's the same stepping you mention, is it?

Click to expand...

Yes, it is.

Yes, AGP 66, PCI 33. You know what I meant. How can I make sure it's set properly? I'll go install SiSoft Sandra and see if I can check from there.

Check. I think it's the i845E chipset that limits it to PC2100.

from the Asus website:
* Supports Intel Pentium 4 socket 478 processors
* Intel® i845E and ICH4 chipset
* 3 DIMMS slots for up to 2GB of PC2100/PC1600 DDR SDRAM support
* AGP 4X slot
* 2 ATA100 supports up to 4 IDE devices
* 6 USB 2.0 ports
* 6 PCI slots
* C-Media® CMI8738-MX 6-channel audio (optional)
* S/PDIF-in/out interface (optional)

Again, it's an Asus P4B533. No suffix or anything, just P4B533.

Maybe that was written before PC2700 was mainstream, do you have a recent BIOS flashed for your board? Go to the asus homepage and download several of the newer ones, read the readme files and then play around with each. One or more may work better for your particular setup, (and not always the most recent).

kestrel said:

Maybe that was written before PC2700 was mainstream, do you have a recent BIOS flashed for your board? Go to the asus homepage and download several of the newer ones, read the readme files and then play around with each. One or more may work better for your particular setup, (and not always the most recent).

Click to expand...

I think it's the most recent BIOS. I checked not too long ago. I'll go take a look.

edit: ooh, they're up to 1014. I'm running 1011 ATM. No major changes though, just little bugfixes like NIC boot devices, and support for high multipliers and hyperthreading.

edit: Just updated it to 1014, I'm about to try OCing to 2.9GHz (where it usually quits)

edit: I tried FSB 160, VCore 1.625V, CPU:RAM 5:4... no luck. ntoskrnl.exe is either missing or corrupt. Then I tried something new, I disabled the secondary IDE controller - not that I can live without my DVD and CD-RW, but just for experimentation - and I didn't get the missing or corrupt error. Win2k crashed halfway through bootup, nonetheless.

Groan...

BUMP again. Still at 2.7GHz, here.

Yep, you're hitting the wonderful world of drive corruption. I get that message when I pushed the FSB too far on my old board (PCI didn't lock). When you disabled the controller and some errors went away, it definitely sounds like you're pushing the controller too hard. Have you been able to find out if the PCI bus is actually locked?

I also get some errors similar to that now, when I push the CPU without raising VCore, but I'm not too familiar with Northwoods, what's the most you can raise VCore by, without risking SNDS? Anybody have an idea of what's safe?

My thoughts are that you're getting corruption on the drive (even though the controller is on the motherboard, it's still on the same PCI bus), or that your chip isn't stable enough. Try bumping VCore just a _bit_, not too much, and see how it goes. That, and see if there's a way to verify PCI bus speeds.