Prescott 560 Quest for 4.5Ghz

I got the cooling (Xtreme III watercooling).
I got the CPU temps (right now 37C idle, 44C load w/Prime95 @ 4Ghz).
I got the memory (Corsair XMS DDRII 667 matched).
I got the PSU (OCZ 520W w/33A on 12V rail).
See the sig for mobo and card.
Now let's get this thing rolling!

I have two issues:

1) I can't seem to push the memory past 660mhz (even though it's rated past that, with others getting more). I saw 730mhz once when playing with previous cooling system. This is so odd.

2) If I push to the 4.2 range, while passing may benchmarks with AWESOME scores, the display tends to flicker and die/lockup system under heavy gaming (Joint Operations @ 1600x1200 w/4xFSAA and full details). I get ~40FPS with the system running at 3.6Ghz with all of those options.

Current Stable settings:

CPU Freq: 222 (x18=4.0Ghz, 888mhz FSB)
DRAM Freq: 593 (296mhz)
PCI: 33.3mhz
PCI-X: 100mhz (even though there's a reported problem here, see below)
Mem Volt: 2.00V
Chipset Volt: 1.5V
CPU VCore: 1.550V
FSB Termination: 1.2V


These settings below seem to post, but as soon as XP switches from DOS screen to GUI Splash screen, the system reboots/dies. Like there's an issue with with the graphics card:

(everything above same except):
CPU Freq: 240 (x18=4.3Ghz, 960FSB)
DRAM Freq: 320 (640mhz)

Hell, the system will post with 250 CPU Freq (4.5Ghz, 1000mhz FSB) with the above. Just locks up/dies at XP's graphics splash screen same as 4.3Ghz.

I'm not running that high of a CPU Freq, so it's go to be something else. The PCI-X graphics is reported to have an issue with anything higher then 258 or 260mhz with this video card I have. I'm no where close to that, and running into issues.


I'm new to overclocking, so I don't know the limits of things too well. I've turned the 12V rail on the PSU, bumping it to a measured 12.7V (up from 12.1V factory).

I just don't know any safe voltage limits, or what to raise/lower/measure/etc. I'm going for very stable under gaming (hours of gaming on end), but I believe I have the tools to get more then I am (thanks to several here for the help!).

Thanks in advance!

You are already running pretty high vcore. I doubt you are going to make 4.5 gig. Maybe try raising N/B voltage.

batboy said:

You are already running pretty high vcore. I doubt you are going to make 4.5 gig. Maybe try raising N/B voltage.

Click to expand...

N/B = Northbridge? I don't see that anywhere. Everything listed above are my only options. Well, perhaps it's in another part of the bios.

The reason for running the vcore at that spec is because that's what I've seen other screen shots have it at. I'm not sure what vcore I have to/need to run at.

What PSU? That sounds like a power issue.

Sentential said:

What PSU? That sounds like a power issue.

Click to expand...

Listed above: OCZ PowerStream 520W. Lots of people love this for overclocking. Plenty of amps on the 12V and 5V rail.

http://www.newegg.com/app/viewProductDesc.asp?description=17-104-152&depa=0

It's called N/B voltage with Abit... looks like it's called chipset voltage with Asus. Maybe try 1.65v to start out with. I have used up to 1.8v, but I don't know if that's safe yet.

eduncan911 said:

Listed above: OCZ PowerStream 520W. Lots of people love this for overclocking. Plenty of amps on the 12V and 5V rail.

http://www.newegg.com/app/viewProductDesc.asp?description=17-104-152&depa=0

Click to expand...

Nvm LOL...we have the same PSU. And yes I know what its capable of

batboy said:

It's called N/B voltage with Abit... looks like it's called chipset voltage with Asus. Maybe try 1.65v to start out with. I have used up to 1.8v, but I don't know if that's safe yet.

Click to expand...

Ok. I think my only options are 1.5 and 1.6V. I'll try it.

I think it's more related to graphics though.

Aiight. After many failed attempts, the 1.5V vs 1.6V for the "Chipset Core" doesn't make a difference. Results are the same as described above. XP crashes the system (full shutodwn/reboot/BLUE SCREEN) when the GUI splash screen starts to load up.

Now, I'm able to get a stable 4.2Ghz now by using the AI Booster logic, and setting it to 15% overclock (system idles at 3.6Ghz and 33C, then jumps to 4188mhz and 42C under max load). The system gets the highest score now in benchmarks, and the game I'm testing it with (J.O.) gets the higest refresh rates in this setting then I've seen. Seems this would be optimum (cp ck).

I tried the net step up, 20% overclock profile, but the system won't boot with that.


What I don't like about the AI booster is it forces my memory to only 460mhz. Is there some memory benchmarking program out there? I'm debating if running 4Ghz w/ 680mhz on memory is better then 4,2Ghz w/460mhz on memory. But the benchmarks tell me it's the latter that performs better (4.2Ghz w/460mhz memory

In this AI mode, the bus speed goes to 230mhz max where setting things manually tends to force me only to 222mhz. So I must be missing something.


Argh... I still think it's a graphics problem, not letting me get past the XP splash screen cause it's perfectly in sync when that screen should appear, I get the blue screen of death @ 4.5Ghz.

Its not a graphics problem, the fact that your pc bsod's at windows boot is cause the pc is so unstable at that speed, i think that 4Ghz and memory running fast will give you better performance for games, you wont miss the 200mhz.

If you havent already, download Prime95, just google it and it will be the top link or some. Run two instances of that 12 hours should do it.

I have only seen the new E0 stepping prescott overclocked to 4.5ghz range without extreme cooling. Otherwise you need vapochill or something like that to reach that high.

[BBE]Jimbob said:

If you havent already, download Prime95, just google it and it will be the top link or some. Run two instances of that 12 hours should do it.

Click to expand...

Yep, I use Prime95 in testing the temps and longevity (~1 to 2 hours each time). It's heavy gaming that crashes the system

ar7786 said:

I have only seen the new E0 stepping prescott overclocked to 4.5ghz range without extreme cooling. Otherwise you need vapochill or something like that to reach that high.

Click to expand...

So you say you've seen E0s clocked at 4.5Ghz with some decent cooling? I have the cooling, and that's my goal! Argh, so yes we are missing something here. What motherboard and ram did they have? Got an article/link?

I don't plan on going any higher then 4.5Ghz.

I've noticed in this AI mode that the cpu's voltage is lower then what I was manually setting it to when not in AI mode. I wonder if I was pushing too much voltage through it...

So you say you've seen E0s clocked at 4.5Ghz with some decent cooling? I have the cooling, and that's my goal! Argh, so yes we are missing something here. What motherboard and ram did they have? Got an article/link?

People have been talking about it right here at this forum
http://www.ocforums.com/showthread.php?t=338018
and elsewhere
http://xtremesystems.org/forums/showthread.php?t=46325

Thank, but that's a different CPU. Yep, classified the same Prescott class but using 478 socket, and also rated much lower in heat consuption then my LGA775 processor (74W if I recall, vs. my 115W).

Doesn't really matter on the heat output, as the water cooling system seems to be handling it very well. Highest temp I've seen was 47C when I booted to DOS at 4.5Ghz. I just can't seem to get into Windows at anything above 4.2Ghz.

Edit: I just clicked the 2nd link, about the newer 570J.

Just read where Nvidia's SLI is a joke to me (see link in sig for more detail). So it looks like I'm scrapping my SLI plans for a new mobo.

Time to start thinking longevity. So it looks like I'll go ahead and pick up one of the newer models of this board, the P5AD2-E version as it supports 1066FSB for the newer LGA775 cpus next year. I'm really disappointed that Asus doesn't list those differences on their site when I just bought this a few weeks ago.

Perhaps this new mobo will get me the overclocks I'm looking for, as many others are showing excellent promise with the "-E" version.

Also since I've pretty much decided to scrap my SLI plans, I'll go ahead and pick up an ATI X800 as well as there seems to be less PCI-X issues with them, then NVidia cards.

I've read in quite a few places that ATi PEG cards do better at higher FSBs then nV PEG cards. The PCI-E bus speed reported may only be for the lanes originating from the southbridge, not the PEG (Pci Express Graphics) lanes originating from the northbridge.

Also, don't confuse PCI-X with PCI-E

Ah, that's right. Forgot about PCI-X, ut saw that on a few sites and relayed it here. My bad.

Yep, I've read the same thing about the ATI handling bus speeds better then nVidia as well. And, I think I am seeing that problem right now even though others are saying this isn't a graphics problem.

If it's not a graphics problem, then what else is there to try, turn up, apply more voltage to, etc. I've pushed the memory hard, the vcore hard, unlocked buses, etc. Nothing matters.

I think I'll just go for a highend ATI card, even though 512MB versions are due out next year.

Well, it could sort of be a video problem... the PCI-E frequency lock does not work properly on these i915/i925 chipsets. I've had my best overclocking success with the PCI-E frequency BIOS setting left on "auto".

batboy, you've played around a fair bit with s775 I believe, do we know for sure if the PCI-Express frequency lock works (or at least partly works) for both the northbridge and southbridge lanes or only the southbridge lanes?

Would it be possible to try running TexBench and Serious Magic's texture download benchmark at different FSBs to see if the PEG data transfer rates change at different FSBs?

I don't know the answer to your question. The PCI-E lock does not completely work... it's sort of managed if you use auto.