I originally ordered a Q9550 for my new build but the supplier I ordered from got their Q9450s in this week and they said the Q9550s weren't coming for another 3 weeks. So...after having a review of the situation it was an easy choice to change to the Q9450. Almost £120 cheaper for half a multiplier difference (8*333MHz for the Q9450 versus 8.5*333MHz for the Q9550). So, I should get the CPU and RAM in at some point next week.

Now, this brings me onto the point of this topic. Originally I hadn't intended to overclock the chip, but from what I've been reading it seems it'd be criminal not to. The Q9450 has a locked multiplier, the maximum clock depends on what you can push your FSB to. From what I've been reading it seems 460-470MHz is the absolute limit for anyone with any sort of dreams of stability. That's an increase of about 40% over standard, for a clock of 3.76GHz. I'm not looking to go as high as that, I'm thinking about the 3.3-3.4GHz range. This would require an FSB in the region of 410-425MHz (an increase in the region of 25% over standard). Assuming I can reach a stable 3.4GHz clock this leaves me with a question about the RAM.

I've ordered DDR2 1066MHz RAM, so if I run it at 1:1 RAM:FSB, assuming a 425MHz FSB, it'll be clocked at 950MHz. If I run at a 5:4 RAM:FSB ratio the RAM will be running much closer to its maximum, at 531MHz.

So, my question is this: Which would be the better choice for speed: 1:1 or 5:4?

It's been a while since I did any overclocking so I'm a bit out of the loop when it comes to the new chips, so I'd appreciate any input.

When I get the stuff through I'd like to keep a record here of some benchmarks at standard and at different clocks to try and provide some answers with hard numbers, so once the stuff comes through expect to see some nice pictures. At the moment the only pics I've got are of some poor cable management and a massive graphics card with no CPU or RAM

The rest of the spec is as below:

CPU: Q9550
CPU Cooler: Arctic Freezer 7 Pro
Motherboard: P5K-E WiFi
Video Card: Radeon HD3870X2 1GB DDR3
RAM: 2*2GB Corsair PC2-8500
OS HDDs: 2*74GB Raptor (RAID0)
Storage HDD: 1TB Hitachi 7K1000
PSU: Corsair HX620W
DVD-RW Drive: Lite-On DH-20A1S-18C
Case: Antec P182
OS: Vista 32bit Home Premium
Keyboard: Labtec Ultraflat
Mouse: Razer Copperhead
Monitor: BenQ FP241W

Very nice setup! Best of luck with it, and keep us posted with the results!

OT:

1) Speed over timings, Intels apparently love speed, so I'm guessing 5:4
2) Voltage and Temps, 45nm duals have become voltage limited, not temperature limited. Keep your voltage under 1.36 and your temps under 70C at load for a long healthy CPU life.

FYI: It sounds like you've heard of the FSB limitations on quads, 460ish for max 24/7. This is as the quad puts substantially more load on the northbridge (IIRC). While substantiated under 65nm C2D's, you're an early adopter to 45nm quad warfare, so let us know what you find.

Got the CPU and RAM in last night and fitted them (hungover) this morning. Spent most of the day setting it up and trying to fix a network issue (which I haven't yet resolved). Anyway, I've been running it at standard clocks most of the day but I did put a quick experiment with very disappointing results. Went for what I thought would be an easy 3GHz clock (375MHz FSB, 470MHz RAM), but I got an error within 2 minutes of running the Prime95 multicore stress test ("FATAL ERROR: Rounding was 0.5, expected less than 0.4
Hardware failure detected, consult stress.txt file."). There doesn't appear to be a stress.txt file produced. Anyway, it's massively faster than my old system (obviously), but I was really expecting 3GHz to be a breeze and for it to go on to much more. Looks like I might just have got one from a bad batch

The Q9450 should do about 4GHz without Problems but only if your motherboard can handle a very high fsb.

Witch cooler do you have?

I'd say 4 GHz on a Q9450 is a bit of an exageration, more like 3.8.

Either way chances are it's just an odd BIOS setting stopping you hitting 3 GHz.

I think the problem might have been due to a lack of adjustability in the BIOS. My CPU isn't fully supported by the current latest BIOS so not all the options for vcore adjustment are available. Hopefully once a new BIOS comes out to support the C1 stepping this'll be fixed. I posted about that in the SuperPI mod thread.

I agree with Jakg though, I reckon somewhere between 3.7 and 3.8 would be the limit for the chip, but I'm hoping to get to 3.4 fully stable 24/7.

Cooler is an Arctic Freezer 7 Pro as in first post.

What BIOS version are you running? I assume it's the latest 1006?

Mine was shipped with 0901 (or 0906) and 1006 hasn't been out long, but has several Overclocking-Layout features...

EDIT - Latest version is 1012...

You can download the stuff for your mobo here, and the BIOS direct from here.

Quote from Jakg :

What BIOS version are you running? I assume it's the latest 100something?

0703 according to Everest. Only the C0 stepping Q9450 is officially supported by the current BIOS.

Bollocks - just updated to the latest BIOS you linked to Jack but I didn't think it would reset my boot devices so it tried to boot from the wrong drive. I've gone in and reset the boot devices and boot order but now it doesn't boot. It comes up with an error message like "Boot device couldn't be found. Please reboot or insert a boot device and press any key". I'm sure the boot devices and priorities are the same as they were before

Don't you have to go into the BIOS and set SATA to RAID or something THEN set the HDD Priority to "RAID:Whatever" THEN set the boot order to the HDD's?

Quote from Jakg :

Don't you have to go into the BIOS and set SATA to RAID or something THEN set the HDD Priority to "RAID:Whatever" THEN set the boot order to the HDD's?

Yeah, I've done that. Set the SATA configuration from IDE to RAID then set up the boot priority as floppy -> DVD -> RAID boot volume.

I am in the middle of something so can't check the BIOS, but is the Boot order set to something like "RAID:Raptor"? if it just says Raptor, then it doesn't think it's in RAID, it may also be worth investigating the "Hard Drive Priority" tab.

God I can't remember the way around my own BIOS :X

Yeah, it's set to RAID:Volume0 (default RAID volume name...noob ). I've also rechecked the configuration on the Intel RAID controller at boot and it seems fine.

Worryingly though, I booted with the Vista DVD in to take a look at the repair menu and according to it there are no instances of Vista to repair. That can't be a good sign.

The exact error I get is "Reboot and select proper boot device or insert boot media in selected device and press a key". From a quick Google search it looks popular but it's gonna take some time to wade through the crap. Looks like I might just reinstall Vista and be done with it. Oh, well...2 days of configuration down the drain

Hmmm, finished reinstalling and initial configuration and for some reason this has fixed my slow network problem from the other topic - no idea why. Anyway, BIOS vcore options look the same but I'll investigate more tomorrow.

Had another play about at the weekend and got much better results with the new BIOS. Been running at 3.2GHz (400MHz*8) with the RAM at DDR2 1000 for a couple of days now with no problem. Stock voltages across the board. Was stable on Prime95 for 6 hours and seems a healthy bit faster. Temps at full load are around about 60 degrees over the 4 cores, which is higher than I expected but they may drop after a while. Think I'll leave it at this just now and maybe push more in the future.

nice! I sat with my e6750 at 8x400 for quite a while. The quads need more northbridge voltage as the FSB gets higher afaik. Grats on the nice OC, and great rig.

Your cpu cooler isn't quite up to the task of heavily overclocking the quad core, you'll get a lot more headroom if you go a bit more exotic with a nice Scythe Ninja or Thermalright tower heatsink..

Had to order a new HSF because the fan on my previous one (Arctic Freezer 7 Pro) stopped spinning

So, I've now got a Xigmatek HDT-S1283 with Arctic MX-2 Thermal Paste. Already I'm seeing a reasonable improvement in temps over the Freezer 7 Pro (in the neighbourhood of 5 celcius at full load, the average over the 4 cores is now 57 celsius compared to over 60 celsius). Will hopefully see if I can get a little more speed out of it now.

I've got my Q9400 (essentially the same as the Q9450, just with half the L2 cache) comfortably to 3.4GHz with a Freezer 7 Pro on stock volts. If I want to go higher I'll need to get better RAM (I'm on DDR2-800, didn't originally intend to overclock it).