At what point does memory speed limit CPU overclocking?

[corrado33]

I have an old PC that I'm messing around with overclocking. It has an old Intel E8500 lga 775 CPU with DDR2. The motherboard supports DDR2 1066 with overclocking "ability" of up to 13## something or other. Anyway, I had some old DDR2-800 laying around so I figured I'd use that for now. In attempting to overclock my CPU, I could get it up to a FSB of 390 (mult of 9.5) or so, but as soon as I'd try 400, it'd crash. I tried 1.35V, but wasn't willing to try any more. However, I'm not sure the voltage is the problem as 390 runs fine at 1.3V. I haven't tried to go lower to optimize the overclock yet, but I haven't seen any problems at these settings. In skimming the internet, I found that it's very difficult to bring your FSB above your memory speed (dual channel). Is that the wall I'm running into?

 

Oh, the E8500 can overclock to much higher than what it is now according to the internet. Most people see at least a 1 GHz improvement where as I'm down at 550 MHz or so. My temps are fine as I've got a beefy cooler on it. 

 

I haven't messed with OCing the memory yet. I need to read more before I try that.

[Ronda]

What does core clock have to do with memory clock? The only thing in common is base clock, but you're not changing that, are you? You probably have gotten yourself a below average chip.

[SLAYR]

With the fsb  it is more then just the memory that is affected the pcie slots will also be affected, try reducing the ram speeds though so they run at about the same speed as originally and it shouldn't affect them then.

1 minute ago, Ronda said:

What does core clock have to do with memory clock? The only thing in common is base clock, but you're not changing that, are you? You probably have gotten yourself a below average chip.

FSB is the predecessor of bclk, and fsb speeds affect the cpu, and ram speeds.

[corrado33]

38 minutes ago, SLAYR said:

With the fsb  it is more then just the memory that is affected the pcie slots will also be affected, try reducing the ram speeds though so they run at about the same speed as originally and it shouldn't affect them then.

FSB is the predecessor of bclk, and fsb speeds affect the cpu, and ram speeds.

Ah so you're saying that when I adjust FSB I'm also "overclocking" the memory as well. How do I unlink them? (What's typically the setting, I know it'll be different for each bios.)

[SLAYR]

4 minutes ago, corrado33 said:

Ah so you're saying that when I adjust FSB I'm also "overclocking" the memory as well. How do I unlink them? (What's typically the setting, I know it'll be different for each bios.)

You can't "unlink" them, just downclock the ram when you increase the fsb. 

[corrado33]

1 minute ago, SLAYR said:

You can't "unlink" them, just downclock the ram when you increase the fsb. 

I don't know, I'd consider that "unlinking." I'm sure you have to flip a switch that says "Use normal FSB speed" or "Manual Control" (more than likely it's "Auto" and "Manual") at least that's how it is on my modern board. 

But good to know, I'll look at that.