1 (edited by Nintendo Maniac 64 26-04-2018 05:46:40)

Topic: PSA: Phenom II x4 is faster per-GHz than 45nm Core2 Quad / LGA771 Xeon

I had come into possession of an LGA775 motherboard and had purchased a cheap 45nm LGA771 quad Xeon in hopes of using it as a dirt-cheap HTPC build for 1080p SVP, but from some quick testing it turns out that SVP is one of those rare programs that actually perform better per-GHz and per-core on a Phenom II.


This isn't a super-scientific test or anything, but I did use the same video clip with identical settings on the same OS configuration and the same HD5870 GPU (heck the Xeon system actually had more RAM thanks to 2GB DIMMs; the Phenom II used 1GB DIMMs). but it certainly was a result that I did not expect and therefore I figured I would share my results.  Note that the charts were largely made for my own comparison use as I couldn't run both PCs at the same time so I needed a way to refer to my own results (I only have one HD5870, so I had to swap it between both PCs).

Now admittedly the Phenom II had faster RAM since it was using DDR3-1333 vs the Xeon's DDR2-800, but hey if that's enough to make the Phenom II faster then so be it - having support for both DDR2 and DDR3 was a key differentiate for the Phenom II series after all.


I do also know that the Phenom II has an integrated memory controller as well as a true native quad-core design when compared to the Core2 Quad's / Xeon's dual-die + fsb configuration, so it wouldn't surprise me at all that any memory-sensitive heavily-multithreaded applications would be faster on the Phenom II, and even more-so when the Phenom II can use DDR3 memory.  While I knew SVP loves "moar cores!", I didn't realize that SVP cared that much about the memory sub-system as well.

Post's attachments

Phenom II x4 @ 3GHz.png, 20.54 kb, 590 x 257
Phenom II x4 @ 3GHz.png 20.54 kb, 78 downloads since 2018-04-26 

Xeon L5420 @ 3GHz.png, 20.21 kb, 590 x 256
Xeon L5420 @ 3GHz.png 20.21 kb, 92 downloads since 2018-04-26 

Re: PSA: Phenom II x4 is faster per-GHz than 45nm Core2 Quad / LGA771 Xeon

To me results look very similar performance-wise. Curious how much power was drawn with these configurations?

3 (edited by Nintendo Maniac 64 26-04-2018 10:23:44)

Re: PSA: Phenom II x4 is faster per-GHz than 45nm Core2 Quad / LGA771 Xeon

James D wrote:

To me results look very similar performance-wise.

The Phenom II being faster is most apparent with the CPU utilization for the combination of "half pixel + 14 px."

Nevertheless, the thing is that 45nm Core2-based CPUs pretty much always have faster IPC.  So the fact that the performance was actually a bit in favor of the Phenom II was not at all what I was expecting.


One thing however is that the Phenom II overclocks to 3.6GHz at 1.3v quite easily when combined with the beefy 140w AM3 stock cooler.  However, overclocking the Xeon is limited by the motherboard (which can't handle an FSB past 430), my RAM (I don't have any DDR2-1066) and the CPU cooler (stock Intel heatsink with copper plug).


James D wrote:

Curious how much power was drawn with these configurations?

I can measure that, though no idea how soon I'll get the results.  Nevertheless, they're totally not an apples-to-apples comparison as the Xeons tend to be higher-binned for lower voltages than consumer Core2 CPUs, and the Xeon I'm using is even a low-voltage model but is then overclocked from 2.5GHz to 3GHz.

The Phenom II however is a black edition dual core model that's been unlocked to 4 cores which then requires an extra 0.025v to 0.0375v to run stable but then is underclocked from 3.4GHz to 3GHz.

While I do know what the lowest rock-solid stable voltage is for the Phenom II @ 3GHz (1.125v), I don't know what it is for the Xeon @ 3GHz as I haven't really done any real stability testing outside of making sure it doesn't insta-crash after running a CPU stress test for about a minute or so - I just know that it doesn't BSOD at 1.1v.