[svoltmer]

Hi,
I am using a Asus P4P800-E Deluxe with a P4 2.8Ghz @ 3.36Ghz. I have installed some GEIL PC4000, but when I try to set then RAM timeing for 500Mhz the machine restarts or locks up. I have tried raising the RAM voltage to the max my bios allows 2.8v and set the CAS latencies to the manufacturers settings (2.5, 4, 4, 7) and even raised the vcore to 1.5v with no luck. What should I look into now? I have it running stable at FSB = 240, vcore = 1.45 DDR = 400Mhz vram = 2.6v. Any help will be greatly appreaciated!

[batboy]

On an Asus mobo, DDR=400 is the 1:1 memory ratio. The only way you can run DDR500 speed is to raise the FSB to 250 MHz. Perhaps that's what you did... I wasn't clear from your post. Make sure your AGP/PCI is locked to 66/33. Raise the vdimm to 2.7v. Check idle and load voltages and temps at your current speed and settings. Asus tends to droop vcore a lot under load with the Prescott.

[svoltmer]

OK, but why does Asus have settings for all the standard DDR speeds? (ex 333Mhz, 400Mhz, 500Mhz, 533Mhz) When would I use them?
I have tried fsb=250Mhz with DDR=400, but even with my vcore at 1.5v and vram at 2.8v the system hangs under heavy load. My temps are 45C NL and 55C under max load.

[batboy]

Asus uses those odd settings for their memory ratio. Think of it this way (remember DDR speed is double the RAM frequency). At default speed of 200 FSB using PC3200 RAM at default DDR speed of 400, then the memory ratio is 1:1. If you set it to the 500 setting, that's the 4:5 ratio (but this usually don't work if you are using a 800 bus CPU... that's more for a 533 bus CPU). At the default 200 FSB if you were able to use the 4:5 ratio, then that would give you DDR500 speed. The 533 DDR BIOS setting is the 3:4 ratio and so forth. The settings don't mean that's the speed your RAM runs, it's a ratio that is tied to the FSB speed. Clear as mud?

[svoltmer]

Got it. Thanks! Now I have it running at FSB =245 DDR=400 with my vcore =4.8v and my RAM timings set to what GEIL suggests; 2.5, 4, 4, 7. It will go through 3D Mark intill partway through one of the "cpu tests" then the program crashes. Should I up my vcore or is it a RAM issue? And if it is RAM what should I look at? I am kinda spooked about going above a vcore of 1.5. My temps under load go up close to 60C. Suggestions? Thanks!

[batboy]

I'm assuming vcore is 1.48v and not 4.8v? Unless you are undervolting a lot, I'd be careful about raising vcore much more. Check idle and load vcore. Asus tend to droop vcore under load. To make sure it's not RAM, try 2.7v vdimm and 3-4-4-8 timings just to see what happens. With a Prescott, 60 degrees load CPU temp is ok, but you might wanna look into a little better case ventilation. Read the article listed in my signature.