Architecture/Overclocking

The CPU up close

The E4000 line

As we mentioned earlier, Intel’s new E4000 line of processors, including the E4300, are based on their new “Allendale” core. Allendale is based largely on Conroe, only a few changes have been made to the processing core to make it cheaper for Intel to produce.

The most important change that has been made to make the CPU cheaper to manufacture is that Allendale ships with less cache. It has been estimated that around 60% of Conroe’s die consists of its large 4MB L2 cache, so with Allendale sporting half the L2 cache of Conroe, its die is considerably smaller. Another feature that’s been removed from the Core 2 Duo E4300 is virtualization. With virtualization, multiple operating systems can be run “virtually” from a single machine. This technology is particularly important in the server space, where one machine could host Windows, Linux, and Novell to run as a web server, database server, domain controller, etc all from one box, all running on different operating systems. Each virtual server would be completely independent and secured from the others. Virtualization is seldom used in the desktop market, so losing this feature honestly isn’t a big deal to most enthusiasts.

E4300 box on left, note virtualization is missing

Fortunately the E4300 still supports 64-bit and execute disable bit, as well as Intel’s Enhanced SpeedStep technology.



Another important change is that Allendale sits on an 800MHz front-side bus (200MHz quad-pumped). In comparison, Conroe boasts a 1066MHz FSB. This change reduces peak system bandwidth from 8.5GB/sec in Conroe to 6.4GB/sec in Allendale, but as we’ll show you shortly, once overclocked Allendale is capable of hitting FSB speeds well beyond 1066MHz.

With its 200MHz FSB and 9.0x multiplier, Intel’s Core 2 Duo E4300 runs at 1.8GHz (9.0x200). It’s because of this 9.0 multiplier that the E4300 has been highly anticipated among enthusiasts and overclockers, as you won’t have to hit as high FSB speed to get a high CPU overclock. To hit the 3.0GHz mark for instance, the E4300 needs an FSB speed of just 333.5MHz. In comparison, Intel’s previous budget Core 2 CPU, the E6300, requires an FSB speed of 429MHz. As you can imagine, it’s a lot easier finding a motherboard that will hit 333MHz FSB than one that can go to 429MHz with complete stability. Another bonus of this lower multiplier is that you can OC the CPU to very far levels without having to resort to using pricey memory: good ‘ol DDR2-800 should do just fine.

Overclocking

So how far were we able to push our Core 2 Duo E4300 chip? We started by seeing how far we could push the CPU’s clock speed without adjusting voltage. Armed with our P5B Deluxe WiFi-AP motherboard and a Scythe Ninja Plus Revision B cooler, we were able to hit speeds of 3.069GHz (341MHz FSB) on stock voltage. That’s an effective speed of 1364MHz!

Stock clocks

Stock voltage

Look at that OC!

Once we cranked up the voltage, we were able to hit speeds of 3.582GHz (9.0x398MHz FSB) with our E4300. That’s an FSB speed of 398MHz – just two MHz shy of 400MHz! We needed a voltage of 1.525V to hit that speed with complete stability however.

We could actually boot into Windows at lower voltages, but the system would reboot itself during testing. 1.525V is a little higher than ideal, but our temps were still at acceptable levels so we felt the risk was worth it. We couldn’t get any higher FSB speeds to load without seeing a BSOD.