A64 is better - they come in faster speeds nowadays, plus you get much better enthusiast-friendly motherboards with Socket 939 (as 940 is really for servers, so limited BIOS tweaking). Plus of course you need expensive ECC Registered RAM with the Opterons which makes the A64s much better value for money.
There were boards that were designed for FX socket 940 chips. On one of these, an opteron would perform as well (almost) as an equally clocked A64 for socket 939. With dual channel ram, they would perform better (about 3 to 5%) than an equally clocked 754 chip.
Yes, they do take a slight hit for ECC, it's just not that big.
Several things I have to correct.
1) Opteron 150 is the same speed as FX-53. Athlon 64s do not come in faster speeds, just a wider variety of speeds to choose from. The top Opteron is the same speed as the the top Athlon.
2) 940 is also meant for workstations.
3) If you have no intention to overclock, slot 940 processors are cheaper. Examples: FX-53 939 - 811, FX-53 940 - 649, Opteron 150 - 575. All prices from pricewatch.
In theory, if you're hell bent on putting together an FX-53 system with no real intention of overclocking, even after the added RAM cost, an Opteron 150 would be a better deal than a FX-53 939 based system. Unless your goal is > 2gb of RAM. And an Opteron 148 is the same speed but $250 cheaper than an FX-51.
But if you're taking into account non-FX chips, I agree that A64s are better values in general. I honestly don't know much about overclocking Opterons on a single 940 board. I suspect you might have some good options on some of those boards. I have a dual board, and this system doesn't overclock that far without stability problems, which seems largely due to the SATA controller, but I haven't dug too deep into it.
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Thanks for the input...Hmmm, ok - dont think OC'ing and invalidating the warrant on my new CPU would be something I would want to do right from the start - Im leaning towards the A64's now, price being a big factor. So the Cache size difference doesnt make that big a differnce then?
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Opteron 150 is the same speed as FX-53. Athlon 64s do not come in faster speeds, just a wider variety of speeds to choose from. The top Opteron is the same speed as the the top Athlon.
:redface: I'd always thought the Opteron was a step or two behind the A64, speed-wise. Maybe I should check these things.. My bad...
If you have no intention to overclock, slot 940 processors are cheaper.
Not if you don't look at the FX chips. That's like saying P4s are cheaper than Xeons because the EE chips cost more than Xeons.
I don't generally bother thinking about the FX chips. They're simply far too expensive for anyone to consider buying, IMO. Price/Performance is terrible compared to a 3200+ or a 3400+ or something, plus of course if there's any intention of overclocking (now or in the future) then buying the highest possible speed-bin is rarely the best option.