Overclocking E6400 by 60%
From:
"andrew cooke" <andrew@...>
Date:
Sat, 9 May 2009 18:26:20 -0400 (CLT)
I have a new motherboard (Asus P5Q), CPU cooling fan (Zalman CNPS9500 AT),
and memory (Kingston DDR-800 CL5).
The new board alone is slightly faster (by a few percent). But the memory
allows me to overclock much further than before (I didn't understand
earlier, but I was memory limited). It's now pretty much trivial to run
my E6400 dual core (which is a 2.13GHz CPU) at 3.4GHz. With the faster
memory and board, benchmarks are running nearly twice as fast (the
improvement is more than you'd expect by the increase in clock speed
alone).
Here are the benchmarks, from mprime (prime95):
[1] [2] [3] [4] [5] [6]
768K 20.408 18.241 14.898 17.353 14.254 11.419
896K 24.876 22.116 18.014 21.155 17.390 13.970
1024K 27.775 25.058 20.568 23.578 19.832 15.571
1280K 34.984 31.135 25.311 29.848 24.876 19.717
1536K 42.091 37.696 31.153 35.838 29.813 23.776
1792K 51.313 45.907 37.693 43.665 36.242 28.936
2048K 56.736 56.497 42.449 48.220 40.535 32.298
2560K 74.556 67.344 54.061 63.542 52.445 42.005
3072K 89.958 80.724 66.441 76.359 63.521 50.682
3584K 109.729 98.756 80.448 93.190 77.496 61.782
4096K 122.243 111.042 90.782 103.557 87.006 69.195
5120K 155.761 139.786 112.167 131.977 108.599 86.527
6144K 186.275 164.912 130.115 157.367 127.388 102.715
7168K 232.665 223.349 162.070 195.954 156.536 127.688
8192K 255.999 231.800 181.558 212.689 172.551 139.292
768K 12.167 12.593 12.156 10.155 10.188 7.602
896K 14.285 14.807 14.131 12.061 11.898 8.868
1024K 27.114 20.936 19.060 16.603 16.590 12.834
1280K 20.403 20.009 18.410 17.327 16.803 12.842
1536K 24.219 24.158 22.570 20.488 20.162 15.400
1792K 29.525 28.951 26.523 24.874 23.957 18.281
2048K 32.503 33.430 30.858 27.649 27.169 20.819
2560K 42.824 42.459 38.833 36.412 35.013 26.808
3072K 51.851 52.456 48.089 43.808 42.211 32.735
3584K 63.313 66.375 57.097 53.347 50.151 38.603
4096K 71.242 74.312 67.507 59.918 56.966 43.686
5120K 95.112 98.149 84.860 76.887 71.544 55.143
6144K 119.427 123.165 109.660 96.872 95.226 71.323
7168K 153.167 163.594 137.815 120.865 116.777 90.379
8192K 195.421 201.644 158.536 141.485 128.384 106.770
58bit 4.858 4.156 3.160 4.143 3.141 2.614
59bit 5.042 5.596 3.300 4.233 3.180 2.668
60bit 4.927 5.574 4.385 4.166 3.198 2.638
61bit 5.324 6.084 4.633 4.556 3.467 2.882
62bit 5.648 6.440 4.894 4.820 3.664 3.044
63bit 6.521 7.470 5.684 5.590 4.256 3.537
64bit 8.246 9.383 7.143 7.027 5.341 4.426
65bit 8.547 9.739 7.379 7.246 5.550 4.580
66bit 9.594 11.029 8.418 8.218 6.261 5.161
67bit 9.514 10.910 8.277 8.154 6.217 5.136
[1] Laptop
----------
Lenovo Thinkpad X60
Intel(R) Core(TM)2 CPU T5600 @ 1.83GHz
CPU speed: 1829.83 MHz, 2 cores
CPU features: RDTSC, CMOV, Prefetch, MMX, SSE, SSE2
L1 cache size: 32 KB
L2 cache size: 2 MB
L1 cache line size: 64 bytes
L2 cache line size: 64 bytes
TLBS: 256
[2-6] Desktop
-------------
Intel(R) Core(TM)2 CPU 6400 @ 2.13GHz
[2] CPU speed: 2137.22 MHz, 2 cores (ASUS p5LD2 SE, i945P, 266, DDR2-533)
[3] CPU speed: 2803.53 MHz, 2 cores (ASUS p5LD2 SE, i945P, 350, DDR2-700)
[4] CPU speed: 2137.22 MHz, 2 cores (ASUS p5Q, p45, 266, DDR2-533)
[5] CPU speed: 2807.79 MHz, 2 cores (ASUS p5Q, p45, 350, DDR2-700)
[6] CPU speed: 3400.13 MHz, 2 cores (ASUS p5Q, p45, 425, DDR2-851)
CPU features: RDTSC, CMOV, Prefetch, MMX, SSE, SSE2
L1 cache size: 32 KB
L2 cache size: 2 MB
L1 cache line size: 64 bytes
L2 cache line size: 64 bytes
TLBS: 256
92% Faster
From:
"andrew cooke" <andrew@...>
Date:
Sun, 10 May 2009 12:33:55 -0400 (CLT)
After a bit more experimenting I've settled with a base frequency of
435MHz (which gives a reported CPU speed of 3.5GHz on boot with the fixed
scaling of 8 for the E6400).
Some details in case I ever try to repeat this:
- using "auto" for as much as possible seems to be the best approach
- memory is still the limitation
- 440MHz passed memtest
- 450MHz failed memtest
- dual channel (memory in both yellow slots) appears to be slightly
(5%?) faster than single channel
Also, I tried to understand the Northbridge strap. I am unclear how it is
implemented, but in practice all it lets you do is specify the integer
divider for the FSB. The FSB is related to the base clock via the ratio
of two integers: A/B. So f(FSB) = f(base) * A/B (and B is selected by the
"strap").
Curiously the "A" has values (with some arbitrary scale factor) of 5, 6, 8
and 9 (no 7). While B has values 3, 4, 5, 6 (which ASUS labels as 200,
266, 333 and 400 MHz for some obscure reason).
If you use the integers above (which are the smallest simple numbers) then
you also need an extra factor of 2. For example, given a base clock of
350 Hz, the available factors (including the extra 2) and corresponding
FSB frequencies are:
A
B 5 6 8 9
3 (200) 10/3=1167 12/3=1400
4 (266) 10/4=875 12/4=1050 16/4=1400
5 (333) 10/5=700 12/5=840 16/5=1120
6 (400) 12/6=700 16/6=933 18/6=1050
which are the FSB speeds available (the spaces were missing from the BIOS
display).
But you don't need to bother with this. If you set strap to "auto", the
BIOS automatically lists all the different values available in the FSB
menu (and appears to select the most stable implementation when the
frequency is available by two different A,B combinations, like 700MHz
above).
Anyway, the final results are below. I wrote a small program to calculate
the average ratio between two different configurations for all the timings
given in the prime output. Comparing my current (apparently stable)
setting (3.5GHz) with that for which the chip was originally designated on
my old board (2.13GHz with DDR 533), I have a 92% speedup!
Benchmarks from mprime.
[1] [2] [3] [4] [5] [6] [7]
768K 20.408 18.241 14.898 17.353 14.254 11.419 10.781
896K 24.876 22.116 18.014 21.155 17.390 13.970 13.139
1024K 27.775 25.058 20.568 23.578 19.832 15.571 14.625
1280K 34.984 31.135 25.311 29.848 24.876 19.717 18.418
1536K 42.091 37.696 31.153 35.838 29.813 23.776 22.164
1792K 51.313 45.907 37.693 43.665 36.242 28.936 26.990
2048K 56.736 56.497 42.449 48.220 40.535 32.298 29.788
2560K 74.556 67.344 54.061 63.542 52.445 42.005 39.185
3072K 89.958 80.724 66.441 76.359 63.521 50.682 47.151
3584K 109.729 98.756 80.448 93.190 77.496 61.782 57.491
4096K 122.243 111.042 90.782 103.557 87.006 69.195 64.115
5120K 155.761 139.786 112.167 131.977 108.599 86.527 81.049
6144K 186.275 164.912 130.115 157.367 127.388 102.715 97.008
7168K 232.665 223.349 162.070 195.954 156.536 127.688 119.891
8192K 255.999 231.800 181.558 212.689 172.551 139.292 130.687
768K 12.167 12.593 12.156 10.155 10.188 7.602 6.515
896K 14.285 14.807 14.131 12.061 11.898 8.868 7.647
1024K 27.114 20.936 19.060 16.603 16.590 12.834 11.174
1280K 20.403 20.009 18.410 17.327 16.803 12.842 10.945
1536K 24.219 24.158 22.570 20.488 20.162 15.400 12.987
1792K 29.525 28.951 26.523 24.874 23.957 18.281 15.674
2048K 32.503 33.430 30.858 27.649 27.169 20.819 17.440
2560K 42.824 42.459 38.833 36.412 35.013 26.808 22.932
3072K 51.851 52.456 48.089 43.808 42.211 32.735 27.739
3584K 63.313 66.375 57.097 53.347 50.151 38.603 33.111
4096K 71.242 74.312 67.507 59.918 56.966 43.686 37.790
5120K 95.112 98.149 84.860 76.887 71.544 55.143 47.342
6144K 119.427 123.165 109.660 96.872 95.226 71.323 59.602
7168K 153.167 163.594 137.815 120.865 116.777 90.379 76.225
8192K 195.421 201.644 158.536 141.485 128.384 106.770 86.106
58bit 4.858 4.156 3.160 4.143 3.141 2.614 2.540
59bit 5.042 5.596 3.300 4.233 3.180 2.668 2.623
60bit 4.927 5.574 4.385 4.166 3.198 2.638 2.554
61bit 5.324 6.084 4.633 4.556 3.467 2.882 2.784
62bit 5.648 6.440 4.894 4.820 3.664 3.044 2.950
63bit 6.521 7.470 5.684 5.590 4.256 3.537 3.416
64bit 8.246 9.383 7.143 7.027 5.341 4.426 4.298
65bit 8.547 9.739 7.379 7.246 5.550 4.580 4.480
66bit 9.594 11.029 8.418 8.218 6.261 5.161 5.048
67bit 9.514 10.910 8.277 8.154 6.217 5.136 4.977
[1] Laptop
----------
Lenovo Thinkpad X60
Intel(R) Core(TM)2 CPU T5600 @ 1.83GHz
CPU speed: 1829.83 MHz, 2 cores
CPU features: RDTSC, CMOV, Prefetch, MMX, SSE, SSE2
L1 cache size: 32 KB
L2 cache size: 2 MB
L1 cache line size: 64 bytes
L2 cache line size: 64 bytes
TLBS: 256
[2-7] Desktop
-------------
Intel(R) Core(TM)2 CPU 6400 @ 2.13GHz
[2] CPU speed: 2137.22 MHz, 2 cores (ASUS p5LD2 SE, i945P, 266, DDR2-533)
[3] CPU speed: 2803.53 MHz, 2 cores (ASUS p5LD2 SE, i945P, 350, DDR2-700)
[4] CPU speed: 2137.22 MHz, 2 cores (ASUS p5Q, p45, 266, DDR2-533)
[5] CPU speed: 2807.79 MHz, 2 cores (ASUS p5Q, p45, 350, DDR2-700)
[6] CPU speed: 3400.13 MHz, 2 cores (ASUS p5Q, p45, 425, DDR2-851)
[7] CPU speed: 3488.41 MHz, 2 cores (ASUS p5Q, p45, 435, DDR2-870,
dual)
CPU features: RDTSC, CMOV, Prefetch, MMX, SSE, SSE2
L1 cache size: 32 KB
L2 cache size: 2 MB
L1 cache line size: 64 bytes
L2 cache line size: 64 bytes
TLBS: 256
Not Quite
From:
"andrew cooke" <andrew@...>
Date:
Sun, 10 May 2009 13:37:44 -0400 (CLT)
Hmmm. So it semes I am also at the limit of the CPU. While 435 passed
memtest no problems the system hangs with prime - I assume the CPU is
stalling. And I don't want to over-volt further (auto is already pushing
things close to 1.5V).
Changing to 440 with a x7 CPU factor (3.1GHz) seemed to be stable, but was
much slower (74% faster than base, compared to 92%).
Changing to 425 (3.4GHz) with the faster x8 also seems to be stable, and
doesn't lose as much (86% faster than base, compared to 92%). This is
what I am using for now.
Andrew
Factor of 2 (Northbridge Explanation v2)
From:
"andrew cooke" <andrew@...>
Date:
Tue, 12 May 2009 14:04:02 -0400 (CLT)
The factor of 2 above was the DDR doubling (of course), so here is the
Northbridge explanation again, with that corrected:
I am unclear how the Northbridge strap is implemented, but in practice all
it lets you do is specify the integer divider for the FSB. The FSB is
related to the base clock via the ratio of two integers: A/B. So f(FSB) =
f(base) * A/B (and B is selected by the "strap").
Curiously the "A" has values of 5, 6, 8 and 9 (no 7). While B has values
3, 4, 5, 6 (which ASUS labels as 200, 266, 333 and 400 MHz for some
obscure reason).
If you use the integers above then you also need an extra factor of 2 if
you want the DDR "speed" (because it's *double* data rate). So an FSB
frequency of 400MHz requires DDR-800 memory.
As an example, here are the factors and DDR ratings when the base clock is
350MHz:
A
B 5 6 8 9
3 (200) 2*5/3=1167 2*6/3=1400
4 (266) 2*5/4=875 2*6/4=1050 2*8/4=1400
5 (333) 2*5/5=700 2*6/5=840 2*8/5=1120
6 (400) 2*6/6=700 2*8/6=933 2*9/6=1050
You can see these by setting the clock (350), selecting the Northbridge
strap (200, 266, 333 or 400) and then looking at the list of possible
memory speeds in the BIOS. You should see the values from the appropriate
horizontal line of the table above.
But you don't need to bother with this. If you set strap to "auto", the
BIOS automatically lists all the different values available (and appears
to select the most stable implementation when the frequency is available
by two different A,B combinations, like 700MHz above).
Andrew
More Overvoltage Results
From:
"andrew cooke" <andrew@...>
Date:
Wed, 10 Jun 2009 12:42:50 -0400 (CLT)
The conclusion here is that things appear to get hot quickly once the
"Auto" board config starts to give out.
My base system is FSB 425MHz, as described above, with DDR850 and the CPU
at 3.4GHz. That has been rock solid. CPU voltage appears to be 1.46V and
memory 1.8V.
Memtest results (eg with lower CPU ratio) indicate that I can get to
DDR920 at 2.1V, but the CPU starts to have problems. At FSB 440 things
appear to be stable at 1.55V for the CPU, but the speed advantage is
minimal, CPU temperatures are up, and the CPU fan is always higher (and
noiser) than before. At FSB 450 I need 1.6V and appear to overheat on
prime (system freezes as core temperature reaches high 90s).
So 450 seems to be an upper limit for my CPU with current cooling, and 440
is the closest stable point I have found (3.5GHz). The gain from 3.4GHz
doesn't seem to be worth the worry (increased voltage on CPU and memory,
noticeably higher core temperatures).
So an overclock of 60% (425, 3.4) is "no problem", but 65% (440, 3.5) is
borderline problematic - seems like I have met a fairly steep wall.
Andrew
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