Last year, I bought a Kentsfield core Intel Core 2 Quad Q6600 G0 stepping to overclock, and was able to get a stable 3.5 GHz out of the normally 2.4 GHz quad core. It ran hot, and I modified my Antec Lanboy case to better the air flow. At the time, the Q6600 prices went down from $300 to $200 (on sale at Microcenter), which is good value for money, especially if you wanted a quad core!

Lately it's been unstable and I had to deflate the speed down to 3.2 GHz to run stable, and the temperatures were still in the 70s (Celsius). The Coolermaster Hyper 212 still seem to be doing it's job, so I figured I could remount it. This is no easy task in such a small case, especially since the CPU heatsink requires me to have access to the back of the motherboard, which means taking out the massive (hard to get inside in the first place) EVGA nVidia GeForce GTX260 video card, removing all the screws and wires, and removing the motherboard completely out of the case!

After doing so, temps were slightly cooler, but I still could not get back to my previous overclock of 3.5 GHz! I was content at 3.2 GHz, but was looking around to see what was available.

UPDATE 8/3/2009: I found out that the side panel fan was installed incorrectly, causing the temperature to rise.  I since fixed this - I noticed the Q9550 was also pretty high until I fixed this, which means the instability of the Q6600 at 3.5 GHz was probably not the chip's fault, but mine for causing the bad air flow!

I found that Microcenter had the Intel Q9550 Core 2 Quad on sale for $170, which is a steal! NewEgg is still selling it for $220, and even with Chicago's high 10.25% sales tax, the price was still under $200 ($189.41 to be exact), so I still came out on top. To put it into perspective, it's got 12 MB of cache vs the Q6600's 8 MB, and is 430 MHz faster at stock clocks, and is $30 cheaper!

Another perspective: While NewEgg is selling the Q9550 for $220, they are still selling the old Q6600 for $200! A $20 difference isn't much, when you consider that the Q9550 have many more improvements: faster stock clock, faster FSB (though this can be a bad thing for overclocking enthusiests), 45nm process, lower voltage requirements, and runs cooler.

In my Q6600 review last year, I said that the Yorkfields weren't that good value for money. My how the table turned! What a difference a year makes!

Intel Core 2 Quad Q9550 E0 Stepping
The Q9550 is a Yorkfield core, which I avoided last year because it was a brand new core using a brand new 45nm process (compared to the Q6600's 65nm), and the new cores mean the old ones had their prices reduced. Time went on and sure enough, Intel produced a new revised stepping for the Yorkfield cores (C1 to E0). The E0 is suppose to be better overclockers tha the C1, but according to enthusiest forums, not by much. Slightly lower temperatures as well as voltage requirements make it more attractive than the C1, but again, if you end up with a C1, it wasn't worth crying about.

The new Q9550 also runs at a faster stock speed of 2.83 GHz (compared to the Q6600's 2.4 GHz), as well as a faster system bus (1333 MHz vs 1066 MHz). However, because of the faster system bus, the multiplier is slightly lower (8.5x vs the Q6600's 9x). This mean to further overclock this beast, I will need to raise the system bus even further!

Alas, the Gigabyte GA-P35-DS3L was struggling, but was still a respectable player. When I removed the HSF, I saw that the underside of the motherboard was tinted brown by where the voltage regulators were! The voltage regulators were ovbiously overheating, and the biggest reason is because of the high power draw of the Q6600 (I was running at 1.425v), as well as the fact that they do not have any passive or active cooling. Also, because the mothboard only have a 4-phase power regulator, there was massive amount of vDroop.

The retail box for the Q9550 is much smaller than the Q6600. Upon opening the box, you can see why: the Q9550 comes with a much smaller HSF! I'm not sure what Intel was thinking. It's the same size as the ones included with the Intel Pentium Dual Core E2180s, except that this one does have a copper contact. The rest of the HSF is aluminium, and is about an inch in height! Either Intel is confident of the lower heat output, or it's a sign of the times (cut backs).

Still, the reasons I stated why I picked the Q6600 over the Q9300 (the first Yorkfield CPU) last year is now turned completely on it's head when compared to the new Yorkfield Q9550 CPUs:

Multipliers and Front Side Bus (FSB)
The Q6600 have a high multiplier of 9x. This allows for faster CPU clock rates while keeping the FSB more relaxed. The FSB of the Q6600 is 266 MHz, which gives the overclocker more headroom to push forward. Stock settings are 9x 266 MHz = 2400 MHz (2.4 GHz).

The high multiplier of the Q9550 is slightly lower at 8.5x, while the FSB for the Q9550 is 333 MHz. With a slightly lower multiplier at an already high stock FSB, the stock speed for the CPU is already at an amazing 2.83 GHz!

For overclocking, the Q6600 is simply more flexible, thanks to the low initial FSB. However, because the multiplier is similar to the Q9550, you are looking at slightly lower FSB speeds to reach the same clocks, thanks to the .5x difference of the multiplier.

But you are forgetting that the Q9550 have a few tricks up it's sleeves: lower voltage requirements, lower heat output, and a smaller 45nm process! All which adds to a higher overhead to reach higher overclocked speeds, or run at the same speed as the Q6600 at lower voltage and heat (and hence, more stable).

Price
As stated before, NewEgg is still selling the Q6600 for $200. For $20 more, you can get the Q9550, which improves upon many things: faster stock clock, faster FSB, 45nm process, lower voltage requirements, and runs cooler.

If you have a motherboard and memory to support the higher FSB (for those running the older P35 chipset, you're still covered!), I see no real reason to go with the Q6600.

Proven Mature Process
The good old 65 nm process has been around for a while, but has shown it's age.The 45 nm process had a little over a year to mature, and is proving to be the new king. Intel CPUs using the new 45 nm process have hit higher clock speeds, beyond 4 GHz with dual-core CPUs, and around 4 GHz with quad cores.
 
While the Q6600 was able to hit 3.2 GHz at stock voltage (1.25v), I was able to hit 3.5 GHz at a lower-than-stock voltage of 1.1873v (1.225v is stock).

Unfortunately, either my memory or my motherboard is preventing me from going any higher.

Cache Size
The original Yorkfield (Q9300) came with only 6 MB of L2 cache, while the Q6600 came with 8 MB. However, benchmarks showed when clocked the same, the Yorkfield CPU still had a slight advantage thanks to a little reworking to the new revision. But now that the new Yorkfields (Q9550) have MORE cache than the Q6600 (12 MB now), combined with the slightly faster reworked core, it's no contest.

I called it a draw last time because the Q6600 could have been faster in some tasks due to the larger cache size it had over the original Yorkfields, but now, that advantage is taken away.

Installation
Installing the CPU into my Gigabyte GA-P35-DS3L rev2 motherboard was a snap. You just lift the lever and the latch, place the CPU into the socket, and then fold down the latch and then the lever. This holds the CPU down in place.

Installing the heatsink was pretty easy, too. The thermal paste was pre-applied to the heatsink base from the factory. Just line up the bracket and push in the pins.

Removal of the heatsink will require you to have a flathead screwdriver. All you do is take the screwdriver to the plastic posts and twist to pop the pins up.

Installing aftermarket heatsinks can vary depending on the manufacturer and model. Thanks to the large size of most aftermarket heatsinks and the placement of the pins, it can be hard to get access to them. This is especially true when the motherboard is already installed inside a case. The CoolerMaster Hyper 212 I used requires me to gain access to the bottom of the motherboard to secure it, meaning I would have to take the motherboard out of the case if I need access to swap out the CPU! What a hassle!

Overall, the plastic pins and post are not as durable as previous mounting methods used by AMD and Intel’s own Socket 478 CPUs. The plastic posts are easy to snap off, and with repeated uninstalls and reinstalls, the plastic tabs will wear out. In fact, a few wore out on me when I was fiddling with the stock Q6600 heatsink.

Overclocking
While the standard 2.83 GHz clock speed will satisfy most people, I love being able to squeeze out as much performance as I can from relatively inexpensive parts.

Many people have reported that they can do at least 3.6 GHz at the stock voltage of 1.225v, while some can do 3.4 GHz. This is very impressive, considering they are using the stock cooler!

When I first overclocked this CPU, I stayed at the stock voltage, armed with the large Hyper 212 heatsink, I was able to get 3.5 GHz at the stock voltage, mimicking everyone else's results. With a large HSF, temperatures were relatively low (for a quad core) - 40c idle, 65c loaded (Prime95, 4 cores, small FFTs).

To get to 3.5 GHz, I left the default multiplier at 8.5x and raised the FSB to 412 MHz, while raising the voltage for the memory to 1.9v (1.8v is stock), and +0.2v to the MCH (chipset). The FSB was also given a boost by +0.2v since it was originally made to top out at 333 MHz.

I am far from my goal of 4 GHz, but I believe my memory is limiting me, as well as the motherboard and limited air flow in a small Antec Lanboy case.

My next upgrade is 1066 MHz memory and a better case (looking at a CoolMaster HAF 932 - my friend bought one, and it is very impressive, though pretty big). If I find that my motherboard is limiting me, I may upgrade to a Gigabyte GA-EP45-UD3R, which will have better chipset and MOSFET cooling, as well as a newer chipset (P45 vs the P35 I have now). The P45 is known to hit higher system bus speeds using lower voltage and a 45 nm process (compared to the P35's 65 nm). This is starting to sound familar, isn't it?

UPDATE 8/4/2009: I started UNDERVOLTING at 3.5 GHz, and I found that the lowest 24 hr Prime95 stable voltage is 1.183v!  That's actually 0.042v lower than stock!  This also lowered temeratures to 38c idle, and 58c load!  It is definately either the motherboard (FSB/MCH) or the memory (DDR2-800) that is limiting me.  The FSB is at 412 MHz, which puts the memory at 824 MHz.  Again, the P35 chipset wasn't really meant to see 400 MHz normally, so I have yet to see which component is actually limiting me.  I've ordered 1066 Mhz memory modules, so I'll update you with the results!

UPDATE 8/5/2009: The memory came, and it's definately the motherboard, since I was not able to go any higher than 413 MHz FSB, which does not overclock the 1066 MHz memory at all (826 MHz at this speed).  I went ahead and ordered the Gigabyte EP45-UD3R motherboard, along with a smaller mid-tower CoolerMaster HAF 922, and not the full tower HAF 932 I originally wanted.  This is because it is $50 cheaper, and because NewEgg is offering free shipping (the HAF 932 would have cost $25 to ship!).  I was also able to purchase the proprietary fans (bought 2 extra 200mmx30mm fans) from CoolerMaster's own site for a total of $35 with shipping.  This mean the case and extra fans still ends up cheaper than the full HAF 932 would have cost me.  Overall, this minor CPU upgrade just became a full computer build... memory, CPU, case, and motherboard!  Anyone interested in a P35-DS3L that's slightly singed but still working, and a well-broken in Q6600 guaranteed to do 3.5 GHz at 1.4v, 6 GB (2x 1GB, 2x 2GB) DDR2 memory, and a slighty dinged Antec Super Lanboy case? :p

UPDATE 8/18/2009: I bought a new Gigabyte GA-EP45-UD3R motherboard, which comes with a 6-phase power regulator (vs the P35-DS3L's 4-phase).  It comes with a massive heatsink for both the P45 chipset as well as the power regulators, so cooling to the power regulators won't be an issue.  Also, the P45 chipset uses a 45nm process, vs the P35's 65nm process, which runs cooler, requires less voltage, and should allow for faster FSBs.  In all, I was able to OC the Q9550 to 4GHz!  8.5x 471 MHz (FSB) at vCore 1.35v.  Temperatures hit 70c using Prime95! That's really hot, but room temperature was at 88F (no air conditioning).  I was able to get 63c when I had the AC on (room temp fell to 76F).  I was able to get 4.25 GHz (8.5x 500 MHz), but it ran too hot for me to feel comfortable.  With water cooling, I bet I can run at that speed on a daily basis!

This chip and motherboard is an amazing value performance combo!

Performance
Using Fresh Diagnose's benchmark module, I was able to get some numbers from my old Q6600 (sorry, couldn't get it to run stable at 3.5 GHz at time of benchmarking), as well as my Q9550.

Q6600 2.4 GHz (stock)
DryStone ALU - 11703 MDIPS
WhetStone FPU - 11770 MWIPS

Q9550 2.83 GHz (stock)
DryStone ALU - 13824 MDIPS
WhetStone FPU - 18806 MWIPS

Q6600 3.2 GHz
DryStone ALU - 15593 MDIPS
WhetStone FPU - 21392 MWIPS

Q9550 3.5 GHz
DryStone ALU - 17089 MDIPS
WhetStone FPU - 28399 MWIPS


Power Consumption
Here’s the parts list of my rig:

Gigabyte GA-P35-DS3L rev 2.0 motherboard
Intel Core 2 Quad Q9550 G0
CoolerMaster Hyper 212 (heatsink/fan)
Patriot DDR2-800 2 GB (1x 1GB sticks) memory at 5-5-5-16 timings (2.2 volts)
2x Western Digital Raptors at 34 GB each (RAID0)
JMICRO PCI-E controller (for the Raptors in RAID0)
Seagate 500GB SATA drive
EVGA Geforce GTX260 896 MB video card
Seasonic S600 600W PSU
Antec Super Lanboy

They are all wrapped up in Antec’s light Lanboy aluminum mid-tower case. Power consumption was measured with a Kill-A-Watt power meter.

At the stock 2.83 GHz with SpeedStep (idles at 2 GHz), the entire rig sucks up 148 W. Not bad for all those components as well as a quad-core CPU. Running Prime95 with all 4 cores loaded, power consumption rises to a respectable 245 W.

Repeating the test at 3.5 GHz (Speedstep enabled, but voltage stepping is set at 1.225v) yielded an idle (2.4 GHz) power consumption of 165 W. Loaded, the entire rig ate up 280 W. Still not too bad.

UPDATE: I was able to lower the voltage, so power consumptin also lowered!  At the same speed, I was able to stay stable at 1.183v, which dropped the loaded power consumption to 260 W, while it idles around 160W.

Remember that the last time I hit 3.5 GHz with the Q6600 (I had to disable Speedstep), it ate up 210 W idle, and 300 W loaded! The lower voltage and temperature really does make a difference!

Conclusion
The Q9550 E0 stepping CPU is a highly overclockable, and can potentially hit 4 GHz with the right memory, motherboard, and cooling. The temperature of the Q9550 is much lower than the previous overclocker's lust, the Q6600. However, it's still quite high. To hit 4 GHz on air cooling, I can see that you will need a case that will give a near-open environment, like a mesh front, large front, side, and top fans, as well as decent rear fan to pull the hot air directly off the CPU's HSF. Having a mesh front will also allow the HSF fan to pull fresh air from the front instead of relying on the cool air coming from the bottom fan, which is already heated by the HDDs, chipset, and video card.

This is why I am looking into the CoolerMaster HAF 932 case (Google it!).

Despite the high temperatures, I was able to keep the CPU overclocked at 3.5 GHz inside of a slightly modified Antec Lanboy case (I added a fan on the side panel) and rock solid and stable (tested by running Prine95 on all 4 cores for 12 hours). The temperature is still at a safe 65c, but again, a bit high for my taste. With the side panel off, I can get it down to 60c, which means I definately need a better case, and perhaps lap the base of my current HSF, or even add a better fan.

The only other negative is the power consumption. While it’s not a green CPU, it’s respectable for a quad-core at stock speeds and voltages. However, once you start cranking up the speed and voltages, power consumption rises exponentially. It's still a much more of a power sipper compared to the Q6600, which is a testament to the smaller process and lower voltage requirements.

It’s a great CPU for bragging rights, as well as computational-heavy projects. It’s also great for next-generation games. It’s not something you’d want to keep on 24/7 unless you can afford the bills and can stand the glares from environmentalists. All in all, if you were looking at a quad-core CPU, you already knew what you were getting into in the first place. If you just need all the CPU power you can get at a low price, the Q9550 represents that sweet spot for price and performance.

Recommended: Yes