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The Athlon II X4 series is an excellent low cost alternative to its big brother, the Phenom II X4. I have run several tests and compiled the results in a comparative format. The Athlon II shows some weakness – about -25% averaged in a heavy multitasking environment as compared to the Phenom II, but is within .25% in a non-multitasking situation. For general purpose and gaming oriented computing it is hard to beat, fairly cool running and not the power hog many think it is.
A WARNING: BIOS, BIOS, BIOS!!! Do not assume you need to update, and if you do be prepared to revert. When I first installed this CPU I did not update my bios and I had full functionality except for the core temp sensors reading -254. I decided to update and lost the ability to clock past 3.4 and also the ability to lower the NB multiplier (that bios rev. for some reason is no longer available for download). Many BIOS resets and even a processor swap or two may be necessary to get where you want (you could also get a low clocking CPU and then it is a futile battle). Remember this!! Some modern BIOS actually reduce functionality. This was only a warning not a suggestion. I bear no responsibility if you have a problem; this was a kind of public service announcement.
Power usage and heat
The Athlon II CPU at stock voltage (1.4v) only burns about 18 watts more than the 905e (1.15v), and at the same voltage burns 2 watts less. As to the heat question, the 620 is 2.7* cooler at the same voltage and 3.8* hotter at stock voltage.
Below are the results of a direct comparison of the Athlon II X4 and the Phenom II X4 with all settings the same. The areas in red and green are load/no load, where red is a heavy load and green is no load, and are used in both charts. The first chart is total average and the second is a heavy multitasking to no load average.
So that is a clock for clock comparison.
The overclock is very dependent on the motherboard used; you must be able to achieve a high HT-ref clock!
As to the overclock, if you already have a system and wish to upgrade, test your Ref clock for it’s maximum, keeping in mind that you need at least 308 to reach 4.0GHz. You may need to lower your multipliers (NB, HT and memory) for this. After 3GHz you will probably need to add voltage to the core.
Validation at 3.9 VALID was easy, as well as error free crunching (WCG) and Folding. Stability was another issue. From time to time I had a reboot.
Here are some shots of what I consider a good OC for this CPU.
I used 667 DDR2 on a Biostar AM2+ MB for this testing as I was looking at this as a low cost upgrade option for those with little cash and still riding a dually or an older 65nm quad.
As a side note, these make excellent HTPC processors when stock clocked and undervolted:
These temps recorded using Artic Cooling AF64 HSF
I went as low as 1.12v stable.