P4C800 Overclocking question

  • Thread starter Thread starter Darren M Taylor
  • Start date Start date
D

Darren M Taylor

I have a p4c800e mobo with a p4 2.6Ghz CPU
I have 2*512MB DDR 400Mhz memory chips

When i try and use the overclocking facility in the BIOS (5,10, 20% etc) the
cpu frequency increases, HOWEVER, the memory frequency drops to 333

Anyone any ideas why this should happen?
 
"Darren M Taylor" said:
I have a p4c800e mobo with a p4 2.6Ghz CPU
I have 2*512MB DDR 400Mhz memory chips

When i try and use the overclocking facility in the BIOS (5,10, 20% etc) the
cpu frequency increases, HOWEVER, the memory frequency drops to 333

Anyone any ideas why this should happen?
Click to expand...

The BIOS doesn't do a good job of showing the memory frequency.
To see what it is, you could try a utility like AIDA32 or similar.

To compute the actual frequency, take

Actual_CPU_FSB
______________ x BIOS_Value_Of_Memory_Frequency
Nominal_CPU_FSB

(Note: When BIOS reads DDR333, use DDR320 in your calculation)

Example:

You have a P4-C FSB800 chip. FSB clock is 200MHz (quad pumped this
gives 800). You decide to raise the FSB to 250MHz. While this
is happening, the memory frequency reads DDR333.

250
___ x DDR320 = DDR400
200

So, while the BIOS displays 333, the memory is actually running
at its rated 400.

The reason the BIOS could be dropping the "displayed" memory clock
value, is to keep the memory in spec.

HTH,
Paul
 
don't use the automatic overclock setting. use jumperfree manual instead,
then you can set mem speed to 400
 
I agree, use manual. The auto settings do increase CPU speed at the
sacrifice of memory speed to maintain stability. However I found with
my p4p800dlx that I can easily achieve 20 percent OC with a CPU:mem
ratio of 1:1, 238 bus speed using corsair PC3700 & a P4 2.8C. Above
this I get Prime 95 errors and would need faster ram.

Locust
 
If you over-stress the RAM and its timings the system drops the
corresponding clock speed to keep the system running. Is it safe to say
that you have inexpensive/off-brand RAM?
 
Darren said:
I have a p4c800e mobo with a p4 2.6Ghz CPU
I have 2*512MB DDR 400Mhz memory chips

When i try and use the overclocking facility in the BIOS (5,10, 20% etc) the
cpu frequency increases, HOWEVER, the memory frequency drops to 333

Anyone any ideas why this should happen?
Click to expand...

You probably have the memory on auto so when you increase the FSB faster
than 400, the memory's max rating, the mobo drops it down to the next
multiplier that'll keep it under 400.

Go to manual settings if you want to force it above 400.
 
end user said:
I agree, use manual. The auto settings do increase CPU speed at the
sacrifice of memory speed to maintain stability. However I found with
my p4p800dlx that I can easily achieve 20 percent OC with a CPU:mem
ratio of 1:1, 238 bus speed using corsair PC3700 & a P4 2.8C. Above
this I get Prime 95 errors and would need faster ram.
Click to expand...

I'm not getting any errors with a Celeron 2.4 overclocked to 2.9 GHz (20%
overclock).

Is this a function of the chip model or the individual quality of this CPU
chip? Does anyone else have experience with this?
Thanks
 
Thanks for the tip. I was overclocking my P4C800-E by 10% with memory on
auto. After changing it to manual and setting the memory tweaks, my
benchmarks jumped considerable.
 
Darren M Taylor said:
I have a p4c800e mobo with a p4 2.6Ghz CPU
I have 2*512MB DDR 400Mhz memory chips

When i try and use the overclocking facility in the BIOS (5,10, 20% etc) the
cpu frequency increases, HOWEVER, the memory frequency drops to 333

Anyone any ideas why this should happen?
Click to expand...
Reason for drop are already explained in the other replies.
I would however suggest not to use auto overclock (in %), but manual. This
provides a lot more flexibility.
- set overclock to manual
- disable SPD memory settings and set to 400 MHz (1:1)
- set AGP/PCI to 66/33.
Now increase the frequency progressively (max 5 points at a time) and check
for stability.
When you start to get errors or crashes, reduce frequency again to the last
stable level.
If you find now the speed is not high enough, reduce the memory multiplier
to 5:4 (333 MHz) and continue increasing the FSB frequency again.
Normally you will get the best results at memory divider 5:4 and FSB at +/-
450 MHz. Then your CPU is overclocked agressively (bust still stable in most
cases) but you DDR is still running at rated speed of 400 MHz.
 
Back
Top