One advantage that springs to mind is lower power dissipation...

I'm not sure about the HT thingy. The important thing is:Will the HT bus be any lower when upgrading from AM2 to AM2+ or AM3?

The HT bottleneck will really only affect an IGP because that is the only way it can access the RAM. AM2 IGPs are very bandwidth starved. Few other components move that much data over HT though.

I've played with AM2+ boards and compared the difference in IGP performance with an AM2 and AM2+ CPU and it is significant.

I've got an AM2+ system with an Asus M2A-VM motherboard. I've tried it with an Athlon 7750 (Phenom I core) and it works just fine. Only thing is HT link speed is 1000mhz, you cannot adjust the multipliers anymore and Cool & Quiet is automatically disabled. Performance wise it felt just fine.

However, HT link speed has no effect if at all on Phenom performance. What matters is the NB speed, which is still 1800mhz/ 2000mhz (depending on chip). As such, besides the loss of the above mentioned features, performance shouldn't be impacted much. Considering a Phenom core is clock-for-clock 30% faster than an Athlon 64 and a Phenom II is slightly faster still, I'd say changing out that 5600+ for a Phenom 550 or something similar would be a huge upgrade.

I'm certainly going to change out my old 1600LE on my system for a Phenom II/ Athlon II soon.

swaaye wrote:

The HT bottleneck will really only affect an IGP because that is the only way it can access the RAM. AM2 IGPs are very bandwidth starved. Few other components move that much data over HT though.

I've played with AM2+ boards and compared the difference in IGP performance with an AM2 and AM2+ CPU and it is significant.

But we could assume that any sane person would be using a dedicated graphics card anyway, so this should be irrelevant, right??

Sure, but IGPs are the primarily HT bandwidth consumer in desktop PCs and HT bandwidth is a big difference between AM2 and AM2+ CPUs/chipsets.

It's something to consider in notebooks. For example, there were some Athlon 64 X2 (aka Athlon Neo / Turion X2) notebooks with the 780G chipset. This gimps 780G because a Phenom-class CPU has ~2x the HT bandwidth. But they also had only a single channel RAM interface. So these babies had zilch for gaming capacity really unless we're talking UT99 at 16-bit color.