The Clarkdale Review: Intel's Core i5 661, i3 540 & i3 530
by Anand Lal Shimpi on January 4, 2010 12:00 AM EST- Posted in
- CPUs
Ridiculously Fun to Overclock
We’ll start off with the obligatory maximum stock VID overclock of a 661 ES Clarkdale using Intel’s retail cooler:
Maximum overclock @ stock voltages (3874MHz)
Maximum overclock @ stock voltages without Turbo
With increased core VID, speeds up to 4.3GHz are possible on the stock cooler:
A 0.1V boost puts you in the 4.3GHz ballpark.
Watercooling
Clock for clock performance of Clarkdale against other platforms may not be impressive, but frequency scaling with good cooling is:
4853 MHz stable comes in with a processor load voltage of around 1.438V. Memory performance is related directly to the QPI link ratio. For best performance, keep the QPI link speed as close as possible to CPU core speed to minimize buffer hold times for lower memory access latency.
12X QPI Multiplier
24X QPI Multi
The bandwidth figures are not stellar on either side of the scale (bear in mind the Everest bench DLL needs an update for Clarkdale). However, the higher QPI multiplier ratio is essentially free for the taking; requiring no additional IMC (VTT) voltage increase until BCLK is increased past 210 or so.
Like Lynnfield and Bloomfield, odd CPU multiplier ratios are more stable than even, although the disparity is less pronounced on Clarkdale. We found that even multipliers needed higher VCore at the same overall processor frequency or needed to be run at a lower overall overclock for stability. We’re not sure on the exact cause of this issue but it’s likely to be related to frequency synthesis within the CPU and downstream logic sampling.
Another caveat with Clarkdale overclocking is that the platform seems to be limited to memory speeds below 1600MHz as soon as you increase BCLK significantly (speeds over 1600Mhz are possible at stock BCLK). We’d hedge bets this is due to the memory controller relying on a preset DRAM clock skew table like Intel’s Front Side Bus architectures of old. The current DRAM frequency ceiling means that you’ll be shooting for CAS 5/6 capable memory between 1300-1600MHz for best performance with 4GB of RAM. 8GB configurations require a loose set of sub-timings, and also a 2N Command Rate to achieve 1600 MHz stable on our sample processor.
Sub-Zero
Bloomfield was hit and miss when it came to frequency scaling at low temperatures. Clarkdale seems to be a different animal altogether:
This is what ‘Clarkie’ is good at..
This screenshot was taken with our cascade cooling the CPU. Evaporator head temperatures were in the region of -115 Celsius. Most Lynnfield/Bloomfield CPUs were out of their comfort zone at these temperatures, but Clarkdale seems to be at home. You still get the occasional cold boot bug, but most of the ES CPUs will run benchmarks right down to the boiling point of LN2 (motherboard permitting). We’ve seen screenshots of 3D benchmarking above 6.5GHz and Super Pi runs edging close to 7GHz. Sounds great, but unfortunately, Super Pi 1M is the only benchmark where Clarkdale is really competitive. Once you’re past 230 BCLK, you have to leave QPI frequency on the floor which hurts memory performance in a big way. Couple that with the 1600MHz or so cap on DRAM frequency and you’ll understand why Super Pi 32m doesn’t fare so well on this platform. 3D performance in Futuremark’s 3DMark05 is just about competitive with the current ‘top’ Bloomfield results if you can run Clarkdale at 6.5GHz throughout the bench. The upshot is that we think there will be more good Clarkdale chips capable of 6.5GHz than there are Bloomfield CPUs that can run 3D benchmarks at 5.4GHz. The funny thing is that P55 motherboards using an NF200 to provide triple CrossFire/SLI might actually be the way to go for benchmarks like 3D Mark 05 if you’re into competitive benchmarking!
While Clarkdale may not be the fastest performer from Intel, it’s probably the most fun to overclock.
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Taft12 - Monday, January 4, 2010 - link
The parent's office PC's aren't bottlenecked by the OS - they're not bottlenecked PERIOD. They run modern productivity apps just fine and would gain little to no benefit from Core i3 (or Windows 7 for that matter).Paulman - Monday, January 4, 2010 - link
Those office PC's you mentioned aren't bottlenecked by the 2GB of RAM. But I wouldn't say that they aren't bottlenecked, "period". What they ARE bottlenecked by is disk I/O, I'm sure. Throw in a good SSD and you would notice quite a bit of speed improvement, and probably a noticeable difference between the 1.6GHz and 2.4GHz machines.The most annoying thing to me whenever I'm using my PC is seeing and hearing my laptop HDD thrash around when launching an app or what not, because everything is held up as a result. Yes, I know it's a laptop HDD, but desktop drives are pretty slow, too.
FlyTexas - Monday, January 4, 2010 - link
SSDs are indeed fast, and make the whole computer feel "snappier"...However, these office machines never shut down (they hibernate overnight). IE8, Word, Excel, and Acrobat are always open and always stay open. Once loaded in memory, the hard drive is hardly used.
I've looked at upgrading them to 3GB of RAM, but they aren't using what they have, so why bother? Most of them use right around 1GB of RAM most of the time.
Could we put 40GB SSDs in? Sure, they are about $130 at Newegg right now... Not the end of the world, until you multiply that times 24 machines. Not a minor expense.
FlyTexas - Monday, January 4, 2010 - link
That is so true. This the first time in a long time that the computers have been "fast enough" for everything we use them for.There was a time in 1993/1994 that we were in this position, running DOS 6 and Windows 3.1 on 486DX2/66 machines, where the move to the DX4/100 or Pentium saw no benefit until Windows 95 came out. I worked in small shop back then, and we demoed a Pentium 66 machine, and saw zero benefit over the 486DX2/66 machines, other than it cost twice as much.
Perhaps in 2002, the Athlon XP machines were "fast enough" for Windows XP and Office XP, that was a nice time as well in the business. A Pentium III 550mhz was my last personal Intel chip until 2006, when I got my first Core2Duo machine at home. I had to work with some Pentium 4s at work during that time, Intel really, REALLY dropped the ball with the Pentium 4, IMHO.
Oh well... I've been doing this a long time, I still remember 5.25" floppy drives, with NO hard drive and those ugly green monitors with Hercules graphics... :)
lowlight - Monday, January 4, 2010 - link
But the 45nm package on Westmere doesn't just carry the GPU. They also moved the PCI-E controller and Memory controller there. I guess the "CPU" is still technically 32nm, but compared to Nehalem, half the "CPU" actually resides on a 45nm package on the chip...You can see a diagram in this Clarkdale review: http://www.hardcoreware.net/intel-clarkdale-core-i...">http://www.hardcoreware.net/intel-clarkdale-core-i...
lowlight - Monday, January 4, 2010 - link
Guess I should have read the whole review... You guys picked it up too! Not many others did though ;)ilnot1 - Monday, January 4, 2010 - link
I swear I've scoured the pages but I don't see your Test System Setup Chart: how much RAM, which graphics card? If it is there and I missed it I wish you could delete posts.Spoelie - Monday, January 4, 2010 - link
It's on page 6I'd like to know the setup of each memory benchmark on page 2. What memory speeds and settings were used for the latency and bandwidth numbers?
Anand Lal Shimpi - Monday, January 4, 2010 - link
All of the CPUs used DDR3-1333 running at 7-7-7-20 timings for that test. I used Everest 1909 (I believe, I'm about 2300 miles away from my testbed right now :-P) and CPU-Z's latency tool to grab the data.Take care,
Anand
toyota - Monday, January 4, 2010 - link
I was looking for it too and its not there.