Dual core sandy bridge to quad steamroller upgrade question

[FearfulSPARTAN]

Hello everyone, I know this may sound dumb and not much of an upgrade but im curious what you guys might think and I know we wont know till the reviews of keveri are here so I just want your guys opinion.

I have a dual core sandy bridge i3 and want to upgrade to a quad for the up coming next gen games. Since everyone is questioning the viability of dual cores iv wanted to upgrade this holiday season I now realize most of my potential christmas money would be spent on an i5 and would prefer to have more money for the steam winter sale. Since I am happy with my dual core at the moment iv wondered if I should hold on to it a bit longer and if steamrollers single threaded performance will reach sandy bridge level because I would prefer to not downgrade on single threaded performance. So what im considering is purchasing an fm2+ motherboard and gathering some extra money when I can in the months after december and hopefully when the athlon x4 770k releases ill purchase that. The question is how much of an upgrade would that be so im asking for your guys opinion, also to note I dont have a job at the moment or my decision would be much simpler.

 

[FearfulSPARTAN]

I now realized I put question in the title and this isnt a question... my mistake.

 

[ShintaiDK]

Steamroller will not match SB in same core performance. And Steamroller will still have scaling penalties when going over the module amount of threads. And they are only 2M/4T. In short, its a terrible downgrade compared to an SB/IB quad.

Either throw in an SB/IB quad in your current system. Or simply upgrade to Haswell.

 

[mikeymikec]

I'd consider getting an i5-2400 or something similar first- or second-hand instead, it's a much cheaper upgrade to quad core than a board + cpu + ram change, unless the relative pricing is extremely different where you live. Less upgrade work as well, and presumably your current rig is reliable.

 

[laputan machine]

I'd say keep it, the hyperthreading will keep it relevant a while longer. That 7850 should be the bottleneck in games, not your i3.

 

[SPBHM]

I'd consider getting an i5-2400 or something similar first- or second-hand instead, it's a much cheaper upgrade to quad core than a board + cpu + ram change, unless the relative pricing is extremely different where you live. Less upgrade work as well, and presumably your current rig is reliable.

agreed, it would be a good upgrade for games using 4 cores, and a small upgrade for games using 2 cores.

we know nothing about SR performance.

 

[bononos]

Steamroller will not match SB in same core performance. And Steamroller will still have scaling penalties when going over the module amount of threads. And they are only 2M/4T. In short, its a terrible downgrade compared to an SB/IB quad.
.......

What do you mean by exceeding the module number of threads?

 

[ShintaiDK]

What do you mean by exceeding the module number of threads?

When you for example uses 4 theads on a 2 module 4 thread core. Since they share alot of resources. Then you get a performance penalty. Usually in the 10-20% range.

 

[Insert_Nickname]

What do you mean by exceeding the module number of threads?

When you for example uses 4 theads on a 2 module 4 thread core. Since they share alot of resources. Then you get a performance penalty. Usually in the 10-20% range.

The Bulldozer/Piledriver/Steamroller module is not a "true" dualcore, but its not "just" a singlecore either. Its a somewhat hybrid design, more like a singlecore-with-superHT.

The "module penalty" is well established on the internet. It happens because the two cores in the module shares an instruction decoder.

 

[ShintaiDK]

The Bulldozer/Piledriver/Steamroller are not a "true" quad core, but its not "just" a dual core either. Its a somewhat hybrid design, more like a dualcore-with-superHT.

The "module penalty" is well established on the internet. It happens because the two cores in the module shares an instruction decoder.

It also shares the FP unit. Something that starts to be really painful on 2M chips.

 

[frozentundra123456]

I would try to upgrade to an i5 or FX 6300/6350 from a Sandy i3. Unless you wait until Kaveri and it brings big advances (which I do not really expect, except maybe in igp performance), I think going from a Sandy i3 to a 2 module AMD would be basically a sidegrade at best.

 

[Insert_Nickname]

It also shares the FP unit. Something that starts to be really painful on 2M chips.

As I understood it, the FPU unit is chopped in half, one part for each core, that can then be combined to execute AVX/FMA instructions. Or have I gotten that backwards? In either case FPU performance shows a significant gain when you use AVX.

You're quite right on FPU performance being poor (no, not that bad actually) on two module chips. I don't want to think about the one module ones...

Edit: Oh, yes. Wasn't Kaveri/Steamroller to use dual decoders, one for each core in the module?

 

[ShintaiDK]

As I understood it, the FPU unit is chopped in half, one part for each core, that can then be combined to execute AVX/FMA instructions. Or have I gotten that backwards? In either case FPU performance shows a significant gain when you use AVX.

You're quite right on FPU performance being poor (no, not that bad actually) on two module chips. I don't want to think about the one module ones...

Edit: Oh, yes. Wasn't Kaveri/Steamroller to use dual decoders, one for each core in the module?

You got it pretty backwards to put it mildly. No 256bit either like SB got.

 

[Insert_Nickname]

You got it pretty backwards to put it mildly. No 256bit either like SB got.

Looked up the Bulldozer review:

But lookie here:

http://www.anandtech.com/show/4955/the-bulldozer-review-amd-fx8150-tested/2

 

[ShintaiDK]

BD and PD takse 2 cycles to execute 256bit AVX. The FlexFP was nothing but PR like the increased IPC.

A 2M/4T BD/PD/SR got roughly half the FP performance of a 4C SB/IB and around 1/3rd of even 1/4th of a 4C HW.

 

[inf64]

In short, its a terrible downgrade compared to an SB/IB quad.

Read better. The title mentions Dual Core SB, not quad core. I'd say dual core/4T(via SMT) SB has zero chance being faster than 2M/4T SR in pretty much anything but some ST apps like lame,superpi and a few others I can't remember now.

 

[monkeydelmagico]

i5 2400's are selling around $110-130 on ebay. i5 2500 isn't much more and 2500K's sell for around $150. A brand new 3470 is $170.- and 3570k for $190.- at microcenter. All are plug and play option for your mobo. Easy upgrade and will handle anything you throw at it for a few years.

 

[ShintaiDK]

Read better. The title mentions Dual Core SB, not quad core. I'd say dual core/4T(via SMT) SB has zero chance being faster than 2M/4T SR in pretty much anything but some ST apps like lame,superpi and a few others I can't remember now.

Maybe you should read the OPs post then. It mentions an upgrade path to an i5 quad.

 

[inf64]

I'd say i5 SB quad would still be inferior to 4T Kaveri. That's my guess and we will need to see 4T Kaveri tested against i5 SB first.

 

[ShintaiDK]

I'd say i5 SB quad would still be inferior to 4T Kaveri. That's my guess and we will need to see 4T Kaveri tested against i5 SB first.

Yes, just as the FX would obliterate Intel.

Lets look at how it is today:
http://anandtech.com/bench/product/675?vs=288

Chance of Kaveri beating SB? Zero.

Not to mention the OP could get IB for even a bigger lead.

 

[Sweepr]

I'd say i5 SB quad would still be inferior to 4T Kaveri. That's my guess and we will need to see 4T Kaveri tested against i5 SB first.

You'd need a ~35% IPC boost on top of A10 6800's very high clocks (4.1-4.4GHz) to barely match 4C/4T i5 2500k @ stock (3.3-3.7GHz), let alone OCed chips or Core i7 models. Not hapenning.

 

[beginner99]

As was said before get a SB or IB quad of ebay, cl or buy a new one. even a new one will set you back less than a kaveri + new mobo while being way faster.

 

[sm625]

As a simple rule you should not replace your motherboard unless doing so can bring you a > 50% increase in performance compared to an upgrade path that doesnt involve a new motherboard. I'm sure you could acquire a 2500k for a decent price, or even the 8 threaded version.

 

[JDG1980]

Steamroller will not match SB in same core performance.

Probably true, though it might at least reach Nehalem levels.

And Steamroller will still have scaling penalties when going over the module amount of threads.

Pretty sure that one of the main purposes of Steamroller was to get rid of the CMT penalty. There are now two decoders per module, whereas BD/PD only had one.

In short, its a terrible downgrade compared to an SB/IB quad. Either throw in an SB/IB quad in your current system. Or simply upgrade to Haswell.

Steamroller would be an upgrade from his i3 dual core on multi-threaded tasks, but probably a regression on heavy single-thread work, which includes some games. Since he indicated gaming as a primary use case, he's probably indeed going to be better off with Intel.

A Haswell upgrade would be a bad idea - it requires buying a new motherboard for no reason, and the chip runs hotter than the fires of Hell. He'd be better off going for something like an i5-3570K. He can probably use that with his existing SB motherboard (it might need a BIOS upgrade) and it will cost about $220 on Newegg, or $190 if he's lucky enough to have a Micro Center in his area.

 

[Insert_Nickname]

A 2M/4T BD/PD/SR got roughly half the FP performance of a 4C SB/IB and around 1/3rd of even 1/4th of a 4C HW.

Which is to be expected with half the execution resources of the 4 core SB/IB. As I wrote calling a 2 module Bulldozer/Piledriver a "true" quadcore is quite a stretch. Its more of a dualcore-with-superHT. If you look at APUs as dualcores instead of quadcores (I know AMD would very much like you not to) they look a little better.