AM2+ or AM3: Which is faster?

[Speeddymon]

So I've been researching parts for a soon-coming-but-long-overdue upgrade. I always use the AMD Processor lists on Wikipedia as a starting point and then research from there. So I'm looking at the new Phenom II X4 processors and see that the AM3 boards just came out last month. However, I'm a bit confused by the clock speeds listed.

The AM3 CPU's range from 2.5 to 2.6GHz with 4MB or 6MB per core of L2 Cache and 2GHz HT on all 3 CPU's, whereas the AM2+ ones go from 2.8 to 3.0GHz with 6MB L2 on all and 1.8GHz HT on all. I know that Intel and AMD want to get away from the Clock Speed being the number one determination as to what processor is the fastest, so I'm here now to ask, between the AM2+ and the AM3 models, which is the faster CPU at it's stock settings, factoring OUT memory and motherboard?

The reason I ask this specifically is that I do not plan to do overclocking, and I plan to ask similar questions in both the Memory and Motherboard forums once I have an answer here, so that I get the best Mobo and fastest memory as well. I'm already using an 8800GTX, which is more than suitable for WoW, but my framerates are suffering from the CPU and Motherboard I use.

 

[theflyingrat]

For right now, there are just three families of AM3 capable Phenom IIs out.

X3 710/720 - Triple core, 2.6 or 2.8 GHz, 512KB L2 cache per core, 6MB shared L3
X4 805/810 - Quad core, 2.5 or 2.6 GHz, 512KB L2 cache per core, 4MB shared L3
X4 910 - Quad core, 2.6 GHz, 512KB cache per core, 6MB shared L3

Note : That big L3 cache is shared. There are not 4MB or 6MB of cache per core on any of these CPUs.

So far, I've seen the 710, 720, 805, and 810 for sale. The 910 is still exceedingly rare. It looks like there are some vendors with them out there, but it hasn't proliferated the way the 7xx and 8xx CPUs have.

The AM3 family of CPUs still doesn't run as quickly at stock speeds, even with very fast DDR3, as the AM2+ 920 and 940 CPUs. For right now, especially considering the price of DDR2, you're just as well off with an AM2+ PhenTwo rather than an AM3, though the price of DDR3 has been crashing lately. None of them are slow or bad, but the 920 and 940 are the top-flight AMD CPUs from a stock performance standpoint. There are lots of proven AM2+ motherboards out there - you can still use an AM3 CPU in them if you want, too, which is a nice touch.

What CPU and motherboard are you currently using?

 

[Speeddymon]

Right now I'm on a 939 A64 4000+ Single core with a Gigabyte GA-K8NXP-SLI (nForce4) with XP x64 installed. I've got 4 sticks of OCZ Platinum DDR's at 512MB a stick. I plan on trying to get the best Mobo/CPU/RAM from a performance standpoint so I don't have to upgrade for another 2 years, and without spending a grand or more on a Core i7.

So, it seems that the only real differences between AM2+ and AM3 boards are that the AM3 boards won't run an AM2 even with the key pins removed, and that the AM3 boards use DDR3 instead of DDR2.

If the proc is faster, I can deal with the slightly slower DDR2 memory, so it sounds like the best bet would be either a 940 or 940 Black, depending on if I want to have the ability to overclock to higher speeds down the line.

I did say that I wasn't planning on overclocking, but you know how slow a computer can feel 8 months down the road, and by then I will have gotten a return on the investment, so I will be comfortable attempting an overclock, I just don't like to do it on brand spankin' new hardware with the risk I'll burn out the chip and need to drop another chunk on a new one.. Another chunk I won't have until next tax season..

 

[Speeddymon]

Just realized this is in the motherboard forum. My apologies and mistake.

Since I was about to ask about motherboards anyways, what's the general consensus as to the best gaming motherboard in terms of warranty, reliability, overclockability, and stock performance that is an nForce board?

Last time I checked, which was 2 years ago when I had already bought a different motherboard, socket AM2 had _just_ come out, and the best socket 939 board was one of the DFI LanParty UT models.. According to their site, they are still the best Overclocking platform, but I want to verify with someone more familiar. I've seen some up and comers like Foxconn etc that seem to be bargain companies like ECS, but without having much knowledge of the current market, who's to say they (Foxconn) aren't the best overclocking board maker right now?

Edit: After doing a little more research on the DFI site, it seems the majority of the DFI boards are Intel boards, and the few that are AMD boards are crossfire. I've seen 1 or 2 that are AMD and also support SLI, and it's a LanParty JR board. I'm thinking it might be better to get an Asus board this go round? I am asking as I can't get any of the asus sites to load at the moment.. =/

 

[QuietIce]

ASUS has made some very good performers for the 940 CPU's. The M3A79-T and the newer M4A79 are both excellent clockers and rock stable. Almost all companies make a good 790GX or (the better) 790FX chipset board. MSI, Gigabyte, DFI, Biostar, and Foxconn all have good clockers. If the ASUS is too expensive then pick a company - but being like me (building a new main rig every 2-3 years) I'd stick with ASUS this time ...

 

[Speeddymon]

Those boards all seem nice, but if I ever decide to add a second video card to the setup, I wouldn't be able to because of the fact that they are ATI boards rather than nVidia boards, and I run an nVidia 8800GTX.. =/ Do you have any recommendations for a good nForce board? (Note I edited my other post to clarify that I'm looking for nForce boards).

I've read other places that the 980a boards are just a rebrand of the 780a boards and that the 780a's are (not 100% sure) a rebrand of the 730a.. If that's the case, could I just buy a 730a or 780a board and get the exact same performance with a Phenom II 940?

EDIT: I did some more searching and it seems like what I really want is actually going to be an AM3 board due to not wanting to gut it again in 2 years, so I'd be somewhat future-proofing myself by getting an AM3 board and CPU, and it looks like the Crosshair II Formula does what I need. Even though the board comes with an AM2+ socket, their site says that it just needs a BIOS update to get an AM3 CPU working in the board..

I was about to order a Crosshair II and AM3 PhenTwo from NewEgg but decided to call them first to see if they could update the BIOS before shipping it to me.. They won't so I guess I'm heading to Fry's to have them order and update... =/

 

[QuietIce]

The Crosshair is a good choice for an nVidia chipset ...

 

[theflyingrat]

The Crosshair is a good choice for an nVidia chipset ...

At $250, one might as well get a Core i7 system, though! I'm all for using AMD processors, but when you're getting into that price range, none of them even hold a candle.

 

[Speeddymon]

I did take a look at the core i7 processors and boards, and while they do offer better performance, in order to do what I'm wanting to do, I wouldn't be able to get away with a Core i7 CPU for $250. I'm wanting to get the fastest processor I can buy with the latest socket format for the cheapest I can buy it, so that 2 years from now when I upgrade again, I dont have to get CPU/mobo/RAM again.

Whether that means I get an AM2 board, an AM3 processor and DDR2, so I wind up getting mobo and RAM 2 years from now, or I get an AM3 board/CPU and DDR3 memory, so I just need to upgrade the processor 2 years from now, doesn't matter. I just don't want to have to get all 3 at once again in 2 years. The fastest core i7 I can get is still a grand by itself, which is what keeps me away from Intel parts, not to mention that the performance gains of the fastest core i7 over the fastest Phenom II don't warrant the cost difference to me.

 

[juane414]

Whether that means I get an AM2 board, an AM3 processor and DDR2, so I wind up getting mobo and RAM 2 years from now, or I get an AM3 board/CPU and DDR3 memory, so I just need to upgrade the processor 2 years from now, doesn't matter. I just don't want to have to get all 3 at once again in 2 years.

I would say go for an AM3 motherboard and an AM3 CPU. If you get an AM2+ motherboard you will most likely be able to upgrade the CPU in two years, but by that point DDR2 will be pretty outdated I would think. In my opinion, a Phenom II X3 720 at 2.8Ghz would be plenty fast for the next two years, especially if you are planning on overclocking. Quad cores have been around for a while now but honestly I still don't see a real need for them. I haven't even used a computer with a quad core processor yet, and I don't see any reason why I would need to. My laptop handles everything just fine with a 2.4Ghz dual core processor. The only reason why I would consider even a triple core processor would be for folding.

 

[Speeddymon]

That actually brings me to another question. Do multithreaded apps have to be designed to use all of the cores on a 3+ core system or does the app just tell the OS that it's multithreaded and let the OS distribute the workload?

The reason I ask is that I've always wanted to run 2 different distributed computing programs, but with both sitting in the idle thread, they don't work nicely together, so I was thinking if i can tell the OS to put one of them on cores 3-4 and one on cores 1-2 then I'd be set. =)

I would opt for an AM3 board, and DDR3 memory, since the prices I've found are about on par, but I can't find any AM3 boards with an nForce 750a/780a/790a chipset that I can buy _now_.. The closest to release to my knowledge is the Asus M4N82 Deluxe, but it's not due out until Q2 (beginning of next month at the earliest). If I play the waiting game, I'll end up spending the money..

 

[QuietIce]

Not sure about this but I think some are designed for x2 and others for x2+. If it's x2+ then the OS kinda' sorta' handles it, with help from the program code. If it's just x2 then I think it's almost all programming. Again - don't quote me, my understanding of multi-threaded programming is amateur at best.


F@H and BOINC has been tried and just doesn't work out.
Other DC projects may work well together but ...

 

[Malakai]

All my favorite AM2+ boards use AMD 790*/sb750 chipsets =/ Sad nvidia sli'ers.