How much worse will a new CPU perform on an AM2+ mobo instead of an AM3?

The Game Room
1

I’m planning to upgrade an older system that has an AM2+ motherboard (It’s a Gigabyte GA-MA74GM-S2H Rev. 1 in case that has any significance.) with an Athlon II X4 640 CPU, and according to what I’ve read this will result in substantially lower RAM and bus timings than they use in the typical review benchmark, but frankly that’s all just numbers to me and I can’t figure out how much this will impair system performance since there doesn’t seem to be any ready-made comparisons. Does anyone know a rough estimate?

If it’s just 5-10% I’ll just go ahead as planned, but if it hobbles the system speed by something like 20-30% it would end up being more of a lateral upgrade and hence it would probably be worth springing for a new AM3 motherboard while I’m replacing things anyway.

2

Not much. Certainly not 20-30%. There are a lot of DDR3 vs. DDR2 comparisons on the web you might want to take a look at, albeit not for your particular combination. Besides, the AM3 board won’t be supported when the new line of Bulldozer chips comes out, so I personally wouldn’t spring for it at this point.

With that said, why settle for an Athlon II X4 640? You can get the Phenom II X4 940 for the same price.

3

It won’t make a huge difference, probably only a couple percent for most applications.

4

Ah, that’s a good point, I’ll just stick with the board I have then. The Athlon is chosen mostly for power and heat concerns, I’m going to use it in a HTPC with a built-in 380W power supply and ordered a Radeon HD 6850 to go with it because it looked good, so the 125W Phenom line unfortunately falls a bit on the high side. Then again, I reckon I really shouldn’t need anything more than an Athlon for mainly watching Blu-rays and playing games.

5

Ah, gotcha. I’ve always toyed around with building a gaming HTPC, but it’s such a hassle making sure your parts and cables will fit and that you can deal with the heat. I need a Dremel tool…

6

Yeah, I hear you. I actually had to measure the Radeon HD 4830 I have in there now to make sure the new card I ordered wouldn’t end up being too large. I had originally eyeballed a different model but it was about an inch too long, so I had to look around a bit to find a 6850 card that was no more than 8.5 inches.

7

That 6850 card is sweet though. Performance close to a 5850.