What is limiting my overclock?

[RyanGreener]

Okay everyone, since I've decided I won't be upgrading for awhile I want to push my hardware to the limit (as corny as that sounds). Right now, I currently have the rig below. My C2D E8600 is running at a 435 FSB and 10x multiplier, which equates to 4.35 GHz. The VCore is 1.3625 in the BIOS, and once I go past around 440-450 the system just won't post. It makes me wonder why a small change will make it go from complete stability to not even being able to post. I mean I was hoping it'd give me a LITTLE warning when it wasn't enough voltage to the CPU. What's the limiting factor? Is the CPU going to need a lot more VCore? Is the motherboard just not good enough to deliver the power? It's definitely not a PSU issue, or memory issue. I've seen people hit 5.0 GHz with this chip, and I know that it's not possible for every chip/every system, but I was at least hoping I could get it to post with some high speed like that.

 

[Schmide]

Cooling? I'm amazed that you're talking 4-5ghz without mentioning cooling!

Edit: Motherboard/Chipset???/Memory/Memory divider?

 

[RyanGreener]

Cooling? I'm amazed that you're talking 4-5ghz without mentioning cooling!

Edit: Motherboard/Chipset???/Memory/Memory divider?

Proprietary X48 Mobo from Shuttle. Corsair DDR3 1600 MHz. 1:1 FSB DRAM Ratio. Cooling is the ICE unit, but I reversed it's direction and did some case mods so the CPU hasn't hit over 62C yet and the TMax is said to be 72C

I'd like to note that it has past stability tests and it has been perfectly fine at the current settings.

 

[VirtualLarry]

Are you sure that you can do 1:1 ratio with DDR3? I thought that the lowest ratio with DDR3 was 1:2, or 400Mhz FSB:800Mhz RAM, which is DDR3-1600.

 

[RyanGreener]

Are you sure that you can do 1:1 ratio with DDR3? I thought that the lowest ratio with DDR3 was 1:2, or 400Mhz FSB:800Mhz RAM, which is DDR3-1600.

The BIOS permits it, and it runs stable at a 1:1 ratio at current settings. I'm running the RAM at 870 MHz right now...(435x2)

 

[RyanGreener]

Well, currently having a crack at it at 4.45 GHz. I cranked up the NB voltage to 1.35V, and the CPU voltage to 1.4V. This is about as high as I'll go (CPU voltage wise). Maybe the NB will be the key to going higher...

 

[M1A]

I think the key you will find is memory and if you are at 870 thats good, my OCZ ddr3 1600 will not run there stable. Lower you memory and you may be able to go higher.
I had DDR2 with my E8400 setup and was limited with the memory but was at 465GHZ at 1.375v. My experience is DDR3 will not run as high as DDR2 did. But I only have OCZ to compare too.

 

[asher]

I just finished my first OC and when I hit my stock FSB/RAM speeds I lowered my cpu multiplier and started pushing the FSB/RAM up to see how high they would go, adjusting the voltage as I went. Once I knew how fast they would run, and at what voltage, I dropped the FSB down and increased the CPU multiplier again, then pushed the CPU with the FSB knowing that my FSB and RAM could handle the settings they were at.

 

[VirtualLarry]

The BIOS permits it, and it runs stable at a 1:1 ratio at current settings. I'm running the RAM at 870 MHz right now...(435x2)

DDR3-870, or 870 Mhz? See, that's what I was saying, if it's really 870Mhz, then you are at DDR3-1740, which might be too much for your memory.

See what CPU-Z says about the RAM. It's mostly accurate. (Except for AM2 AMD CPUs with half-multis.)

 

[RyanGreener]

DDR3-870, or 870 Mhz? See, that's what I was saying, if it's really 870Mhz, then you are at DDR3-1740, which might be too much for your memory.

See what CPU-Z says about the RAM. It's mostly accurate. (Except for AM2 AMD CPUs with half-multis.)

Nah, CPU-Z says it is running at 435, which would mean its running at 870MHz.