Issues trying to Overclock E8500 on ASUS P5B Board. Details/Screenshots inside

Ok, here are my current system specs:

Intel Core 2 Duo E8500 Wolfdale 3.16Ghz
ASUS P5B Deluxe P965 Motherboard
Zalman 750W Modular Power Supply w/ Heatpipe Cooling
Zalman 110MM 2 Ball CPU Cooler
eVGA GeForce GTX285 1GB Graphics Card
G.SKILL 4GB DDR2 SDRAM DDR2 800

What it is happening is I bump up the FSB to around 400 or so (in small increments from 333) and I can actually get the processor running at 4.13Ghz. The system seems stable at this overclock (no BSODs, freezing, etc) except my gaming performance decreases quite a bit.

I go from 150+ fps to only 25-50 fps in my games at this 4.13Ghz speed. If I reset back to defaults (3.16Ghz) the performance goes back to normal?

I know this issue is related to the RAM somehow, but Im not sure how to fix it. I've manually set the RAM timings to 4-4-4-12, and set the Voltage to 1.9V, but it didn't help at all.

I have also set the CPU multiplier to 9.5, and the CPU voltage to 1.3V, manually.

Also, Ive turned SpeedStep off, as well as I disabled C1E

Im pretty new to OC'ing (I OC'd a previous system and never had to mess with RAM Timings/Voltage) so the solution may be simple to some. From my research, and posting on other forums - I believe this has to do with the CPU/RAM Ratio, but I don't know what to change it to resolve this.

The goal is to get my CPU to 4.0Ghz stable. I purchased proper CPU cooling, etc.

Any help would be greatly appreciated,

Here are some CPU-Z Screenshots:




Thank you

Because after 400mhz on the bus, the board automatically loosens the timings on the northbridge causing a drop off in performance until about 466 fsb. Only after 467 fsb will performance start surpassing 400 fsb. Since you can't change the strap or tRD on the Northbridge, your stuck with either doing 400 or jumping to 467 and trying to go higher.

http://www.thetechrepository.com/showthread.php?t=30
http://www.anandtech.com/cpuchipsets/intel/showdoc.aspx?i=3184
http://www.anandtech.com/mb/showdoc.aspx?i=3208

is this only on that board, or would the same decrease in performance occur on...sayy... a p5q pro?

x.x set out to try to test this a little bit, and had to put down 1.48v (in cpuz) to stabilize a 467 FSB @ 9.5 multi.....was fun to see it at this, but it idles at 49 degrees, and runs full load at 75 degrees, so probably isnt safe >.> im going to drop the multi to 9, and leave the FSB up and do some benches

Some P965 boards let you change the fsb:dram strap which would have the same effect. I don't think it was until the 4 series chips that the tRD on the NB started showing up in the Bios. I'm not really sure since I made the jump from my P5B to P5Q Pro.

Also, no you can adjust the NB tRD using the Performance Level on the P5Q Pro. Though if you don't know what the default tRDs are per strap, you could end up in a worse off condition on performance or a no boot due to incorrect timing on the NB, dram, and cpu. I would recommend reading the two Anandtech articles to get a better idea though.

mastrdrver said:

Because after 400mhz on the bus, the board automatically loosens the timings on the northbridge causing a drop off in performance until about 466 fsb. Only after 467 fsb will performance start surpassing 400 fsb. Since you can't change the strap or tRD on the Northbridge, your stuck with either doing 400 or jumping to 467 and trying to go higher.

http://www.thetechrepository.com/showthread.php?t=30
http://www.anandtech.com/cpuchipsets/intel/showdoc.aspx?i=3184
http://www.anandtech.com/mb/showdoc.aspx?i=3208

Click to expand...

That was all theory back in the early days of CONROE when everybody was trying to figure out the nature of the beast. Most of it has been disproved by overclockers who simply know what they are doing.
The P5B Deluxe was always a flaky board.
Keep in mind too that he is using a late model E0 stepping CPU and most of those BIOS updates for earlier model boards and chipsets that support the newer steppings don't support them all too well.
I think that for now he needs to set his memory modules to the specifications on their sticker and while he is at it set his tRFC (Refresh Cycle) to 52 if he has that option currently available in his BIOS.
Then he should report back with the voltages he is using for his system overall.

Is there a PCIe frequency setting on that MB? It wouldn't be set on auto by chance? Just a thought...

Wait. Multiplier for memory is 1 and cant be changed? No 3:2 or 2:1 or wahtever else? Hes basically running DDR2 memory on 400 mhz. I wana know the everest reading speed on that..

Fill out this BIOS template for the P5B-D with all of your current settings at 420 MHz x 9.5. Also include the VID of your chip (using Real Temp--> 'Settings' page--> Max VID), and a direct link to your particular G.Skill RAM (including whether it's 4 x 1GB or 2 x 2GB sticks)...

It's caused by the well known PCI-e Link Width 1x bug (should be 16x) as shown in your screenshot, google for more info.