P5W DH and memory timings

[ruusnak]

It seems 333 FSB is the biggest number I can set while providing manual timings for the memory. Anything above 333 and the system won't boot, unless I change the memory timings to automatic (SPD). Has anyone been able to supply manual timings when using FSB values above 350 or so? I'm currently running FSB 356 (3.2 GHz), memory is set to 5-6-6-18 (4:5 ratio, 445 MHz). System's fine, just curious... I'd rather run my memory at slower speed and tighter timings (should support 4-4-4-12 @ 400 MHz)

 

[monkeybite]

If you want to run your ram at a lower speed and tighter timings, then you should switch the divider to 1:1 instead of 4:5. At 1:1, your ram would be running at 712Mhz (356x2) at 356 FSB.

SPD will work fine if you aren't worried about getting the tightest timings, but you should definitely be able to set them manually and get the system to boot as long as you're within your ram's range. For example, I am able run my ram at 385 FSB with a 4:5 divider, manual timings (5-5-5-15) @ 960Mhz.

That being said, there is an issue with getting the system to post at higher FSB, even if you've let loosened the timings. This is because we can't change the tRD and tRFC timings in the BIOS (like you can on the P5B for example). This can limit what the system will boot at. Basically the idea is that you will need to loosen tRFC to 35 or 42, and tRD to 7 (or 8 if you are pushing higher FSB's). The reason it will work with SPD enabled is because the system will automatically loosen those timings based on what speed the chip is booting at. Here's the entire thread: http://www.xtremesystems.org/forums/showthread.php?t=111400

You can use MemSet to do this once you are in Windows. The idea is that you boot at a lower FSB, then tweak the timings in Windows with MemSet, and then continue to ramp up the FSB speeds using ClockGen or SysTool.

 

[ruusnak]

Thanks for this... however, it's not what I'm after. My problem is that the mobo refusest to boot if I set the memory timings manually, even if they're the same that using SPD gives. I just wanted to know if someone has succeeded in providing manual timings when using FSB speeds above 350. Even wusy's quide suggests you have to use SPD in case of this mobo....

 

[monkeybite]

Like I said before, I am able to boot with FSB 385 (x9, e6600) with manual memory timings set at 5-5-5-15. I am using Corsair PC8500 ram. Maybe your vDimm or vMCH needs to be nudged up a bit. You should be able to set the timings manually no matter what the FSB speed, I would look towards tweaking voltages a bit.

 

[ruusnak]

OK, I'll try setting the voltages a bit higher. I'm just wondering why my memory did run at higher speed and manual timings (4-4-4-12) when the FSB was at 333 (4:5 memory ratio), using 2.1 V.
And if I set the FSB to 355, and memory ratio to 1:1, the system won't even boot unless I start using SPD timings. And at this setting memory is slower than in the first scenario....
Thanks for the tips!

 

[sean67854]

I'm running @ 400 FSB and I've set my timings manually to 4-4-4-12. I'm running an e6400 with the Vcore @ 1.4250 and Vmem @ 2.00.

My mem is the Corsair 6400C4 TwinX set.

 

[ruusnak]

After increasing FSB and MCH voltages (in addtion to memory voltage - 2.2V) I was able to boot up the machine using 4-4-4-15 timings (FSB 356). Using memset, I set tRFC tp 42 (was 26), and the machine became stable enough to run some benchmarks using PCMark 2005. I ended up with almost exactly the same results as with using SPD timings and 4:5 memory ratio (ends up as 900 MHz). I think I'll settle with the latter, as I don't have to increase any voltages (except memory). My CPU voltage is also at stock value... so I guess I should be happy running E6600 at 3.2 GHz with stock voltages!