2.8E can't reach 3.5ghz. PC4000 RAM the way to go?

Optimummind

Newcomer
My Prescott 2.8E is currently overclocked to 3.4ghz with a FSB of 243. The CPU voltage on the Abit IS7 is 1.6625 V. The DDR voltage is 2.6V on my 2x512mb PC3200 setup. (1x512mb is a no-name Legacy brand and the other 1x512mb is a Mushkin value brand).

Through the BIOS, the 2x512mb DDR400 is running at 2.5-3-3-7 with a 5:4 ratio speed of 194.7mhz (194.7mhz x 2 = 389.4mhz effective).

I've tried to reach a stable 3.5ghz (FSB=250mhz) but running 3Dmark05 causes WinXP to BSOD. I've tried increasing the CPU voltage to 1.7125 V but it's doesn't help. I've tried loosening the memory timings to 3-3-3-8 but oddly, this caused a failure of WinXP to load (whereas booting the system with 2.5-3-3-7 at least got me to a stable Desktop).

What do you think is holding me back? BTW, the CPU is being watercooled by the Koolance CPU-200G and with AC in my room, the temp is around 46 to 47 C.

Will buying the Geil Ultra PC4000 DDR500 ram help me to reach a stable 3.5ghz or have I already reached the limit of my CPU overclock? I don't want to invest around $150 on the Geil PC4000 and find out that I still can't overclock to 3.5ghz.

All help/advice/feedback is greatly appreciated!
 
Optimummind said:
Through the BIOS, the 2x512mb DDR400 is running at 2.5-3-3-7 with a 5:4 ratio speed of 194.7mhz (194.7mhz x 2 = 389.4mhz effective)..<snip>..Will buying the Geil Ultra PC4000 DDR500 ram help me to reach a stable 3.5ghz or have I already reached the limit of my CPU overclock?

Your current RAM isn't even running at spec (400MHz), so no, absolutely do not buy some expensive RAM. You could even tighten up the timings if you wanted. My guess would place the blame on your CPU, but there's always the possibility that the Northbridge isn't getting enough voltage. Make sure your PCI/AGP buses are locked down. 3.4 GHz isn't bad though, and a 600 MHz OC on a P4E is pretty decent as well. If you really want that extra 100 MHz, you might want to shop around for a new (ie 3.0 or 3.2) CPU. Some places might still have Northwood (C) P4's, and those were great (I had a 3.0c @ 3.61 GHz for some time).
 
It's a combination of the CPU and Watercooling system that is holding you back. Your memory isn't even running at spec, so it's not the issue. The Koolance isn't a bad system, but it's not a good performer either. If you want to see what real performance watercooling is about, read XtremeSystems.org WaterCooling forum.
 
Turn the memory divider back up and your FSB down if you want to see how far your current memory can go.
 
kyleb said:
Turn the memory divider back up and your FSB down if you want to see how far your current memory can go.

Do you mean I should set the CPU:RAM ratio to 1:1 and overclock my FSB incrementally to see how far my memory can handle?

At 2.8E, my 2x512MB PC3200 sticks are running at 1:1 at 200mhz and they are fine. I haven't tried taking it beyond 200mhz.

After doing this, if my memory fails around 202, 203, or whatever, what does that mean? After all, I was hitting 3.5ghz on a 5:4 CPU-to-RAM ratio before.
 
Ah, well if you are stable at a 200mhz FSB with a 1:1 memory divider and not stable at a 250mhz FSB with a 5:4 memory divider; then it isn't your ram that is holding you back but rather the motherboard or the CPU.
 
kyleb said:
Ah, well if you are stable at a 200mhz FSB with a 1:1 memory divider and not stable at a 250mhz FSB with a 5:4 memory divider; then it isn't your ram that is holding you back but rather the motherboard or the CPU.

This is what I suspect too.

I have a different question then. If I buy 2x512mb PC4000 RAM and run it in a 1:1 ratio with the CPU, my theoretical memory b/w will have increased from my current 3.11GB/s (6.22GB/s, dual-channel) to 3.88GB/s (7.76GB/s, dual-channel). Will this increased B/W show a noticeable improvement in gaming?
 
I doubt you would notice any improvment in gaming with the extra memory bandwidth. You'd be more likely to see improvement if you bought more 400 MHz RAM than if you had the same amount of a higher frequency.
 
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