Dresdenboys' blog: AMD Bulldozer - Patent based research part 2

[Oliverda]

My thoughts:
Bulldozer having DDR-2 / DDR-3 IMC: Socket AM3 (938 pins)
Bulldozer having DDR-3 IMC: Socket AM3 (941 pins)

Llano is a quad-core design with 480 shaders.
Brazos is a dual-core design.

IMHO 941 pins AM3 CPU will be called as AM3+.

Maybe AM3+ mobos will support separate power planes for each modules in BD.

[FlanK3r]

what about DDR2 IMC? No, please no...DDR2 is in future death. Yes, i have now DDR2 mobo with 965 BE, but for future not, not not. Or, do u can beat DDR3 2100+ in benhcmarks with ddr2 1066 ?

[-Boris-]

what about DDR2 IMC? No, please no...DDR2 is in future death. Yes, i have now DDR2 mobo with 965 BE, but for future not, not not. Or, do u can beat DDR3 2100+ in benhcmarks with ddr2 1066 ?

Depends, with the IMC from Phenom II there isn't much difference.

[Behemot]

Depends, with the IMC from Phenom II there isn't much difference.

Exactly, due to HyperTransport (FSB no longer is bottleneck) the memory does not really matter. The results are almost the same because of the higher the bandwith, the higher the latency. Overall performance in real world apps still the same no matter if you have DDR2-533 or DDR2-1200

Compared to GDDR, the DDR chips stagnate badly

[-Boris-]

Exactly, due to HyperTransport (FSB no longer is bottleneck) the memory does not really matter. The results are almost the same because of the higher the bandwith, the higher the latency. Overall performance in real world apps still the same no matter if you have DDR2-533 or DDR2-1200

Compared to GDDR, the DDR chips stagnate badly

Don't blame the memory chips, the problem is clearly an AMD only issue.
While Phenom II have seen very small advantages of DDR3, Intels LGA 1156 processors have much better bandwidth.

http://www.anandtech.com/show/2832/7

In many cases Athlon 64+ 6400+ shows better memory bandwidth than Phenoms, due to full speed IMC.
Overclocking the IMC cures the problem, but 3.5GHz+ IMC isn't really realistic.


A bit off topic, but just want to show how severe the IMC problem really is in the Phenoms.

http://www.madshrimps.be/?action=get...66&articID=909
66% higher IMC frequency gives 54% higher write performance. With DDR2 800MHz! DDR 400MHz wouldn't be far away in write performance!
Clearly bottlenecked by the IMC. At least read perfomance isn't crippled as much as write.

http://www.madshrimps.be/?action=get...65&articID=909
Overclocking memory gives much less perfomance increase in Nature test than overclocking the IMC.
However, read performance increases, hinting that it's the write operations that the IMC bottlenecks mostly, at least with DDR2 800, with faster memory the IMC should bottleneck read operations even more.

http://www.madshrimps.be/?action=get...67&articID=909
The Phenom II starts getting memory starved already after 1400MHz.


I would love to see these tests with a 3.6GHz Phenom II with at least 1600MHz memory.
And coupled with some real world game benches.

[blindbox]

Don't blame the memory chips, the problem is clearly an AMD only issue.
While Phenom II have seen very small advantages of DDR3, Intels LGA 1156 processors have much better bandwidth.

http://www.anandtech.com/show/2832/7

In many cases Athlon 64+ 6400+ shows better memory bandwidth than Phenoms, due to full speed IMC.
Overclocking the IMC cures the problem, but 3.5GHz+ IMC isn't really realistic.


A bit off topic, but just want to show how severe the IMC problem really is in the Phenoms.

http://www.madshrimps.be/?action=get...66&articID=909
66% higher IMC frequency gives 54% higher write performance. With DDR2 800MHz! DDR 400MHz wouldn't be far away in write performance!
Clearly bottlenecked by the IMC. At least read perfomance isn't crippled as much as write.

Phenom IIs run at 2000+ MHZ IMC at default, at least for the AM3 versions.

http://www.madshrimps.be/?action=get...65&articID=909
Overclocking memory gives much less perfomance increase in Nature test than overclocking the IMC.
However, read performance increases, hinting that it's the write operations that the IMC bottlenecks mostly, at least with DDR2 800, with faster memory the IMC should bottleneck read operations even more.

Well, we are currently using DDR3 for Phenom II, would it be a problem? Bulldozers are DDR3 only AFAIK, only for AM3 mobos.
If you interpolate and make 1066 MHz the basis, anything higher will be the usual 1%-2% improvement from better memory.

Just because it doesn't scale with memory speed doesn't mean it sucks at memory. It simply doesn't need that extra bandwidth.

http://www.madshrimps.be/?action=get...67&articID=909
The Phenom II starts getting memory starved already after 1400MHz.

I think this one explains memory starved better, as it checks scaling at IMC constant 1800 MHZ with memory clocks.
http://www.madshrimps.be/?action=get...65&articID=909

The conclusion: You're not gonna see anymore extra scaling after you overclock memory and IMC beyond.

I would love to see these tests with a 3.6GHz Phenom II with at least 1600MHz memory.
And coupled with some real world game benches.

You can probably see them at Phenom II 965, 975 reviews.

I don't get your post. What problems does Phenom II has with its IMC, apart from unable to run 4 DIMMS without extra volts?

But hey, that gives them a reason for integrating the graphics core : Using up all that extra bandwidth.

EDIT: Oh crap, still not used to firefox 3.6 tabs.

[Behemot]

...

Come on. You play memory write tests on yor computer? Really? If not, why do you think I said in real world apps?

As for Core iX, again, that's what I said: FSB was bottleneck (too thin for both the memory and everyting others - northbridge etc.), now with HyperTransport (or QuickPath) it matters no more. OCed processor has almost the same performance with DDR2-533 and DDR2-1200. The few % performance gain vs. over 100 % frequency gain only proves that

Of course there are some bandwith-hungry apps, but for average use, in 98 % occasions the memory speed has no efect.

[JF-AMD]

what about DDR2 IMC? No, please no...DDR2 is in future death. Yes, i have now DDR2 mobo with 965 BE, but for future not, not not. Or, do u can beat DDR3 2100+ in benhcmarks with ddr2 1066 ?

BD will not support DDR2.

And, believe me, in 2011 nobody is going to want to pay the price for DDR2 because it will be more expensive than DDR3 at that point.

[xlink]

BD will not support DDR2.

looks like I won't be going for AMD the gen unless BD is truly exceptional.

shame, I was hoping for a drop in replacement. ohh well.

[JF-AMD]

looks like I won't be going for AMD the gen unless BD is truly exceptional.

shame, I was hoping for a drop in replacement. ohh well.

Let me rephrase that:

NOTHING IN 2011 WILL BE SUPPORTING DDR2.

Sure, that is an extreme statement, but let's be realistic.

Can you replace a DDR1 processor today with anything faster? Is it worth it?

[haylui]

looks like I won't be going for AMD the gen unless BD is truly exceptional.

shame, I was hoping for a drop in replacement. ohh well.

according to your spec, just drop in an 1090T BE in 2011 and it would be fine....

[LowRun]

L3 cache is slower than Dual-DDR3?

perhaps 2%???
extra memory bandwidth don't boost IPC a lot
since L1 and L2 cache is fast enough to feed the processing units.
compare i5 and i7 and you will see if triple channel is a lot more faster than double channel

according to your spec, just drop in an 1090T BE in 2011 and it would be fine....

There is a multi-quote button for a good reason dude.