AMD Sempron and Athlon II Cacheless CPU Northbridge Overclocking Effects
Update: This is an old article. This was made a few years ago actually. Although these CPUs being reviewed are old now, someone could still have one. So I decided to keep the article posted. This article is by no means a professional review.
AMD put a shared Level 3 Cache and Integrated Memory Controller together on the same power plane with the Phenom cpu’s. Therefore the Processor Core’s clockspeed run a-sync to the Northbridge clockspeed. (From now own I will refer to the L3 Cache and/or Memory Controller as the NorthBridge or NB). By having seperate power planes it can greatly help when it comes to managing power consumption. You do lose performance since the Northbridge runs async to the processor clockspeed usually at a much lower rate. For instance a Phenom II 955 processor has a 3200mhz core clockspeed but its northbridge (and hyper-transport links) only run at 2000mhz. Since the Sempron/Athlon II models has No Level 3 cache, I wanted to see how much of an improvement simply increasing the Memory Controller/NB speed would bring. So that is what this little article is all about.
Note: The northbridge is also referred to as the ‘UnCore‘. Basically the UnCore means its not the main cpu core but does have its own core based frequency. HTT = HyperTransport Link.
Note 2: For marketing reasons AMD and Intel may advertise a 2ghz NB/HTT link as 4000mhz. Basically they can do this since data can be exchanged on the rising and falling edge of each cycle. But the true clockspeed is still 2000mhz.
Below is a simple chart showing the clockspeeds of the cpu core and the nb in this article. I decided to add NB results at 2820 Mhz as well..
Here is the System Setup Summary:
AMD Sempron II 140 – Unlocked to AthlonII x2 4400e @ 3807 Mhz
2x 1GB Sticks of Corsair PC5400 DDR2 @ 282 Mhz 5-5-5-15-20-1T Timings
Dual Channel Memory Controller in Unganged Mode
Western Digital 400GB SataII HD
nVidia 8800GT Video Card @ Stock
22″ LCD with 1920×1080 Desktop Resolution
Yes I know the ram is clocked low but I purposely set it low to see exactly what effect raw memory controller speed made in performance. Obviously the numbers would be better with the ram running faster but thats not the purpose of thise tiny article.