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AMD Phenom X6 1100T and X4 840 tested

by on08 February 2011


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Review: Speed updates, one Phenom is an Athlon

After the X-Mas rush AMD was keen to introduce a few new CPUs. The flagship Phenom II X6 is now clocked at 3.3GHz, Turbo goes up to 3.7GHz, and it still has 64kB of L1 cache per dice for data and instructions, 512kB L2 cache per dice and 6MB shared 3rd Level Cache. The TDP stays at 125W and VCore runs at 1.3500V.

The second introduction was the Phenom II X4 840, which striked us oddly. While in the name suggests 3rd level cache, this one has none. It is in fact the successor to the Athlon II X4 645, with a 100MHz higher clock which now stands at 3.2GHz. Why it's called Phenom instead of Athlon II X4 650 is anyone's guess. The Vcore went up from 1.3500V to 1.4000V, still 64kB L1 cache per dice for data and instructions, 512kB L2 cache per dice and an TDP of 95W.

ASRock 890GX Extreme 3 (provided byASRock)
AMD 890GX/SB850
MSI P55-GD65 (provided by MSI)
Intel P55
ASRock H55M Pro (provided by ASRock)
Intel H55

Intel Pentium G6950, Core i3-530 (provided by Mindfactory)
Intel Core i5-750 (provided by Intel)
AMD Athlon II X4 620/645/X6 1090T (provided by AMD)
AMD Phenom II X6 1055T 95W (provided by ASRock)

Scythe Grand Kama Cross (provided by Scythe-Europe) for AMD and Intel 1156
Thermalright Ultra 120 eXtreme 1366 (provided by Thermalright) for Intel 1366

G.Skill Eco 4GB Kit PC3-12800 (provided by G.Skill)
1067MHz CL7-7-7-20 CR1T 1.35V for Athlon II X2, Pentium G6950, i7-975
1333MHz CL7-7-7-20 CR1T 1.35V for Athlon II X4, Phenom II X4/X6, i3-530, i5-750

Graphics Card:
MSI R4850-2D1G-OC (provided byMSI)

Power supply:
PC Power & Cooling Silencer 500W (provided by PC Power & Cooling)

Hard disk:
Samsung F1 1000GB RAID-Edition (provided by Ditech)

Case fans:
SilenX iXtrema Pro 14dB(A) (provided by
Scythe DFS122512LS

Cooler Master Stacker 831 Lite (provided by Cooler Master)

All tests are performed with XP SP3. As 64-bit software is still not very common, we used the 32-bit version.






We have already stated the specs, so here the CPU-z screenshots.

When Turbo is enabled on the Phenom II X6 then the idle voltage is quite high.




The Phenom II X6 1100T is still nicely under-voltaged. With 0.1V less, it's still stable, but of course you need to disable Turbo.

Phenom II X6 1100T uv


The Phenom II X4 840 aka Athlon II X4 650 disappoints. With its upped VCore of 1.4000V it only manages 1.3250V, which will still shave off some watts but of course 3.2GHz does need power.

Phenom II X4 840 uv



This Phenom was the first we got to 4GHz, booting up with more than 4GHz was possible, but Prime95 was not stable. Our board is not the greatest overclocker but the results are still impressive for a six core CPU.



The Phenom II X4 840 managed a stable 3.7GHz @1.5125V.

Phenom II X4 840 oc





The results with the Phenom II X4 840 are not directly comparable because for our new test rig we upgraded the power-supply to a more efficient one with 80plus Gold certification, which resulted in 1-2% better results for this CPU.


With a little less VCore on default, it does help the CPU to achieve a better performance per Watt also due to the higher clock. Not all CPUs/chipsets have onboard graphics, so the i5-750 runs with our good old HD 4850.



With four or six cores active Cinebench shows us the efficiency of the whole system. Of course without a graphics-card efficiency is better:


Naturally the more you overclock with voltage increase the worse the efficiency will be.




Before we render a conclusion, let's have a look at the overall benchmark results:


Because we had no X4 640 at hand, we just reduced the multiplier by 0.5x to get results. As you can see the X4 645 is just 1.7% faster then it's 100MHz slower counterpart.



Nowadays we have an odd situation at least in Europe. Memory prices are below sublevels, with just 40€ per 4GB kit, but Intel CPU prices have increased while AMD has reduced its prices. An 890GX board is available for about €77, while an H55 board costs around €80. The 4850 1GB card is still available for just 77€ which is not a bad deal. If you are not into overclocking AMD gives you the best bang for your buck, but when you do love to overclock Intel can keep up with the costs while the overclocked CPUs proved to be more power efficient. Also, the 890GX onboard graphics are superior the onboard graphics solution from Intel at least up to the H55 generation.




The flagship Phenom II X6 1100T is not a cheap CPU but considering its six cores and the overall good performance, the €199,75 price tag doesn't soud bad, either. We could manage 4GHz with our sample which is also pretty good, but as the benches show, an overclock to 3.85GHz on our 1055T sample manages to come close to the 4GHz result despite the 150MHz less clock due to higher memory and Hypertransport clocks. Depanding what you want to do, the Phenom II X6 is good choice but the 1100T comes with a price premium.

The new Phenom II X4 840 is of course not a Phenom. It's just an Athlon II X4 650 but suprisingly it's cheaper than the 100MHz slower clocked X4 645. At just €90,- it's clearly a bargain. Of course we always state an AMD is not as fast as an Intel CPU because nobody cares to optimize the code for AMD besides Microsoft, but for everyday work and gaming it's a great CPU and AMD does support its sockets much longer than Intel, so it's more future proof.

When planning a new system, investing more in a good graphics card is always better compared to a slightly faster CPU. The Athlon II X4 650 aka Phenom II X4 840 is our recommandation for consumers on a tight budget.



AMD Phenom II X4 840 



As usualy our benchmark parcours for reference:











Last modified on 09 February 2011
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