p4c800 Deluxe

[Irocnhard75]

I have a P4C800 Deluxe with a 2.8 Prescott P4 1Meg Lv2 Cache.

I am using a pair of kingston hyperx ddr3500 in dual channel mode.
The problem I having is that if I overclock the processor beyond 3100mhz the which it does willingly....it puts the ram speed at 320mhz instead of 400mhz. If I go in manually and set it at 400mhz the computer freezes up before booting into windows xp.
I have contacted Asus about this problem and they do not know, but can only suggest the ram is the problem. But I have done some research before I bought the ram and found that is should be a good match the motherboard.

Any suggestions?

 

[Crashman]

Yes, that's normal. It's supposed to do that. Everything is your fault, that's why Asus can't help you. Well, one thing IS Asus's fault, they used base numbers rather than ratios in BIOS, which confused you.

OK, YOU have PC3500. With a base setting of "400MHz" (DDR400 with an actual clock rate of 200MHz), you're overclocking your RAM to 221MHz (DDR442) when you CPU is at 3.1GHz. Now, you only HAVE DDR433 RAM, it CAN'T HANDLE DDR442 speed at standard settings.

OK, now when your board drops it to 320, it's not actually dropping it to 320. I know, this sounds silly, but it's actually dropping it to 0.8x the CPU bus. That means DDR320 if your CPU bus was still at 200, but DDR354 when your CPU bus is at 221MHz (where you're reaching 3.1GHz).

Now, let me restate it: When you're using an "800 bus" P4 such as your 2.8E, the 320 setting actually means the memory clock is 0.8x the CPU clock.

We go back to the fact that DDR is Double the clock rate, and the P4 bus is Quadruple the clock rate, and you see that 320/2 is 160 for the memory, and 800/4 is 200 for the CPU. And 200x0.8=160.

So, if you were going to go to, say, 3.5GHz with your CPU, you'd get there at 250MHz FSB. Your RAM would have to either run 250MHz (DDR500, using the BIOS setting of 400), or 200MHz (DDR400, using the BIOS setting of 320).

And now you know why it's SUPPOSED to use the 320 setting when you clock that high. It's not actually DDR320, it's actually RAM CLOCK=0.8x CPU BUS CLOCK. Using the 320 setting (which is actually 0.8x CPU bus, not 320 locked), your memory will reach it's rated 216MHz (DDR433) when your CPU is clocked up to 4.05GHz!



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