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AM3 CPU in AM2+ Mobo = significant bottleneck or no?

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June 30, 2009 5:17:33 AM

It's pretty obvious that it hinders its abilities, but how much exactly? I plan on using an AMD Phenom II X4 in a slightly basic gaming computer (dunno if you know what I mean by "slightly" basic), and would rather save some money by NOT buying one of the more expensive AM3 mobos, and getting an AM2+ one. What do you think I should do? I would be using this computer for basic video editing and basic gaming (blizzard games, and they are generally known for considering weaker computers). Thanks a lot in advance for the help.
a c 83 à CPUs
June 30, 2009 5:24:00 AM

An AM3 Phenom II X4 will run the same in an AM2+ board as it does an AM3 board, the only difference is the memory you can use. There is a very minimal performance difference in DDR2 and DDR3, you'll loose at most 5% performance.
June 30, 2009 5:29:08 AM

loneninja said:
An AM3 Phenom II X4 will run the same in an AM2+ board as it does an AM3 board, the only difference is the memory you can use. There is a very minimal performance difference in DDR2 and DDR3, you'll loose at most 5% performance.


thanks a lot. however, lol dont take this as an insult, but how do you know this? because others have said that it bottle necks it and others say it doesn't. it's just that im trying to build a pc without costing too much, but more than that i don't want to sacrifice performance for cost, that is, performance that I would actually use.
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June 30, 2009 10:25:31 AM

i current run a
AM3 Phenom II X3 TripleCore 720 3.9GHZ cpu in a
GA-MA770-US3 am2+motherboard
with 12 gig DDR2-1066
so the answer to your question is no it wont bottleneck it at all as long as the ram u pick is (DDR2-800) and above that is good
cause the ddr2-667 and 533 seem to bottleneck it a bit
in benchmarking i ran the
DDR2-533
DDr2-667
DDr2-800 id say this is min for AM3 chip set before u notice performance difference
DDr2-1066 between this and the 533-667 was a massive improvement in speed +benchmark stats so yea
DDr3-1333
DDR3-1600 -not much noticeable difference between the 2 and the ddr2-1066

so if picking ram go with thee DDR2-800 or 1066 if u don't want to spend alot 1066 for max performance for $$

so hope this helps :D 
a b à CPUs
June 30, 2009 10:51:18 AM

The bottleneck existed when you installed an older phenom (9950,9850, etc) which was AM2+ into an AM2 motherboard, so the HT was not full speed.
THe only difference between AM2+ and AM3 is memory supported, so there is no "bottleneck" but a potential performance gain (minimal) if you upgraded to DDR3.
a b à CPUs
June 30, 2009 11:23:05 AM

well, i don't think that the motherboard itself is more expensive, i think the ram is and its not that much, btw you should get DDR3 board, the memory is getting cheaper and DDR2 is getting more expensive and in the future if you want to upgrade your ram you might be SOL because of price (look at DDR prices compared to DDR2 and DDR3)
June 30, 2009 2:31:47 PM

k thanks everyone a lot
a c 108 à CPUs
June 30, 2009 2:37:27 PM

Not much of a bottleneck - but go AM3

It's only a matter of time before AMD drops the DDR2 memory controllers in AM3 CPUs - dang nice of them to make the effort but they won't do it forever.

And we don't want to hear you in a year complain about that new AM3 CPU that won't work in your AM2+ mobo - LOL
June 30, 2009 6:22:15 PM

This price difference between a 940 and a 955 is $55. That's significant.
September 21, 2009 10:25:07 PM

Do AM3 CPUs work in all AM2+ motherboards?
September 21, 2009 11:47:31 PM

Andy1633 said:
Do AM3 CPUs work in all AM2+ motherboards?


Before I answer, I am no computer tech. I am new to building pcs.

I think you can use am3 cpus in ALMOSt all am2 mobos, because they generally release a bios update that permits it.
a c 83 à CPUs
September 22, 2009 1:45:19 AM

Andy1633 said:
Do AM3 CPUs work in all AM2+ motherboards?


Most AM2+ motherboards have had BIOS updates released to allow the use of AM3 processors, but to be sure you'll need to check your motherboards cpu support list which can be found on the manufacturers website. You also need to consider that a high number of entry level AM2+ boards only support 95W processors, so once again check to see what processors are supported as 125W processors may damage your board.
September 22, 2009 7:02:52 AM

Ye I checked on the asus website and the board I'm looking at buying has 120W support and a BIOS update will add AM3 support.
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a b à CPUs
June 15, 2010 6:52:16 PM

If you need to update the BIOS before you can use an AM3 CPU, wouldn't you need an AM2+ CPU first so that the mobo will recognize the chip so that you can boot up, connect to the internet, download the BIOS? Or am I totally off base?
June 16, 2010 9:59:05 AM

Quote:
If you need to update the BIOS before you can use an AM3 CPU, wouldn't you need an AM2+ CPU first so that the mobo will recognize the chip so that you can boot up, connect to the internet, download the BIOS? Or am I totally off base?


Not always, sometimes it just needs the update to properly recognize it, it may still be bootable but display some incorrect CPU type.
June 19, 2010 4:07:29 AM

kiren said:
Not always, sometimes it just needs the update to properly recognize it, it may still be bootable but display some incorrect CPU type.



i bought a mobo that was am2+ so i could use an amd athlon II x4 630 processor which is AM3 socket. it said that its compatible with bios update...

i was able to install windows vista but the processor type said "amd unknown" then the comp kept shutting off.. i checked the temp of the cpu and it was 80-90 degrees C!!!!

i downloaded the bios update and when i went to flash the bios i got to 77% and guess what.. THE PC TURNED OFF AGAIN!!!!

so what does that mean?

now my mobo is bricked and i have to get another one. thankfully amazon is accepting my return.. i will be getting an AM3 socket mobo this time.

to safely update the bios on am2 to let it recognize am3 cpus i would reccomend doing so ONLY if u have an am2 cpu to do it
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