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AMD A II X2 250 : HT3 vs HT1, perf hit ?

N

NoobyDoo

Senior member
If someone has a Athlon II X2 250 and a 740G mobo ( GA-MA74GM-S2 r4.1), would he gain much by using a, say, 785G mobo instead ? Acc to Gigabyte :
* If you install AMD AM3/ AM2+ CPU on AM2 motherboard, the system bus speed will downgrade from HT3.0 (5200MT/s) to HT1.0 (2000 MT/s) spec; however, the frequency of AM3/ AM2+ CPU will not be impacted.
Click to expand...

Edit : apart from the better graphics.
 
It won't because your CPU doesn't have L3 cache and HTT link is never a bottleneck to start with for non-servers ever since it was first implemented years ago.
 
Disclaimer: I know the Phenom 1's are outdated but I don't wanna get a new motherboard and new RAM right now.

I currently have an Athlon 64 X2 5000+ Black Edition (OC'd to a hair under 3.1GHZ) and am thinking of upgrading to a Phenom 9850 or 9950. I get the same caveat that the OP quoted in their post on my MB's web page.

Would the performance loss be significant? Would I be able to OC?

Also, it is worth paying an extra 50 bucks or so for the 9950? NewEgg has the 9850 for $100 but stopped selling the 9950 a year ago. Other places have the 9950 for around $150 depending on shipping. The main difference seems to be the stock clock speed(2.5GHZ vs 2.6) and maybe TDP. I don't think its worth it.

Maybe someone has 9950 they're not using? I'll take it. I'm sure you used it all of 6 months before upgrading again. So, all though it may be used, there's not a damn thing wrong with it.
 
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Yeah, but would I get the full benefit of the upgrade with the new motherboard? I guess I could live without overclocking. The only really resource intensive thing I do is play GTAIV. Will I notice the HT downgrade?
 
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Even if you get the AthlonII there are gains to be made since the Memory Controller runs at nb speed.

I have a tiny article i'm trying to finish up on what gains to be expected from raising and lowering the nb speed when it comes to cpu's with No L3 cache.

I found out going from 1410mhz nb to 2256mhz nb raw memory based latency dropped a solid 6%. Thats with the ram running at only 282mhz. I purposely left the memory speed low (I don't have any real highspeed ram anyways) to see what can be had by adjusting pure memory controller speed. The cpu is a unlocked Sempron 140 @ AthlonII 4400e 3807mhz with ht and nb in sync. 3x and 4x core AthlonII's will benefit even more with a faster memory controller.

I might post a link to the finished article with all of the benchmark data in the forum here but probably not.


Jason
 
@formulav8: I think the OP got all the help they needed from this thread since it had been a few weeks since someone replied to it before I bumped it. So everybody just pretend I'm the OP now.

With all the advanced CPU discussion going on around here I would think my questions would be really easy to answer. Will I notice the HT downgrade? Will I be able to OC? Not a whole GHZ like you guys. Just past the 3 GHZ threshold. Maybe you're too busy laughing at me for contemplating upgrading to a (slightly)outdated CPU? I don't do advanced computing stuff so I don't need the latest and greatest. I think most CPU development now and into in the near future will be for geek purposes only anyway since a quad core CPU is plenty of computing power for the average user and also for gaming since cloud gaming is on the horizon.
 
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Theres nothing wrong with a Phenom1 cpu. I have a 7550 x2 based on Phenom1 for testing and it does quite well, mainly since the 2MB L3 cache isn't a bottleneck like it is for the 3x and 4x core Phenom1's.

To answer your question, overclocking won't really be limited by HTT 2.0 speeds since the cpu runs on a 200mhz reference clock like all Phenom cpu's do. Only the Memory Controller and Level3 cache will be impacted.

Will you notice it? Well its been shown that ocing the NorthBridge (Which the Memory Controller and L3 Cache run on) can give a solid 10% increase in performance in a couple area's compared to stock 1.8ghz. Gaming will probably show the greatest increase.

Although the drop in performance running at 1GHz HTT compared to 1.8Ghz is definitely measurable, most likely you won't notice the up to 5%-15% performance difference.

So yes, I personally would be content running a Phenom1 or II on a older 1GHz HTT chipset. It would be a huge performance upgrade if your coming from a Athlon X2 based CPU and going to a QuadCore cpu.



Jason
 
Thanks for the info, But I think I'm gonna get a Phenom II. I found some great deals at NewEgg. And all free shipping too. http://secure.newegg.com/WishList/PublicWishDetail.aspx?WishListNumber=18308208 Yeah, I'm a hypocrite. So bite me.😛

I shouldn't have a problem using 2 sticks of DDR2 800(from my current motherboard) and 2 sticks DDR2 1066 together right? I know they'll all run at 800. I read somewhere that 1066 is actually OC'd 800. Is that true?
 
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The Phenom based cpu's supports 1066mhz DDR2. Even if on a 1ghz HTT board it would still provide that feature.

I don't remember if there is a jedec standard for ddr2 to run @ 1066mhz. If not then I guess it could be said that 1066mhz is running out of spec. I honestly would buy DDR2 800mhz or even DDR2 667mhz. It wouldn't be worth the extra cost imo to get 1066mhz ram. Theres not a huge gain by going from 800mhz ram to 1066mhz ram. I guess if you want every last ounce of performance then you may want to get it. You may even be able to get DDR2 800mhz to run at 1066mhz speeds.

If your old board has bios support, then the PII will also run on a original AM2/HT1/HT2 mobo. The cache and memory controller will run at the lower speeds.

I noticed your looking to buy $95 board. There is definitely nothing wrong with that board and its a good board. I have one for testing purposes (I got it when there was a discount and combo buy). But there are other boards very good at a lower price.

To save some money check out this board. I have the 780 chipset version and its a very good tweaker board. It unlocks a single core Sempron 140 to Dual core AthlonII 4400e and clocks the chip to 3807mhz. It has every important tweaker setting to ocing and modifying. Unless that $95 board has some feature or item you want, check out the two boards above.

Just my opinion. 🙂


Jason
 
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How'd you even find that board? I had everything but form factor on "Any" in the power search and it didn't find the one I chose. I had to Google to find it. And I thought I was lucky to find it thinking mATX's were being phased out or something. Actually I think my problem was because the socket part of the power search is confusing. I had all the choices that said AM3 checked.

It looks a lot of people had problems with that board. But my current board is an ASRock and It's worked fine the last 2 years or so that I've had it. So it was probably just a bad batch as some of the reviewers said.

The newest CPU in my current board's CPU support list is the Phenom I 9950. So there's only a BIOS update standing in the way of it supporting the Phenom II? I know the AM3 socket is physically the same as the AM2.

Edit: Wow that was fast! While I was typing this, I filled out a tech support form on the ASRock website and got an answer already. They said my current board won't support Phenom II's.🙁
 
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formulav8 said:
Theres nothing wrong with a Phenom1 cpu. I have a 7550 x2 based on Phenom1 for testing and it does quite well, mainly since the 2MB L3 cache isn't a bottleneck like it is for the 3x and 4x core Phenom1's.

To answer your question, overclocking won't really be limited by HTT 2.0 speeds since the cpu runs on a 200mhz reference clock like all Phenom cpu's do. Only the Memory Controller and Level3 cache will be impacted.

Will you notice it? Well its been shown that ocing the NorthBridge (Which the Memory Controller and L3 Cache run on) can give a solid 10% increase in performance in a couple area's compared to stock 1.8ghz. Gaming will probably show the greatest increase.

Although the drop in performance running at 1GHz HTT compared to 1.8Ghz is definitely measurable, most likely you won't notice the up to 5%-15% performance difference.

So yes, I personally would be content running a Phenom1 or II on a older 1GHz HTT chipset. It would be a huge performance upgrade if your coming from a Athlon X2 based CPU and going to a QuadCore cpu.



Jason
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Jason, can you explain in greater detail the difference between the functions of the HTT and the Northbridge? On my cpu, they are both clocked the same. I always thought the HTT is what connects the cpu to the memory and rest of system. And since AMD cpu has IMC, then where is Northbridge proper? Is it outside of the cpu with the IGP and PCIe controller? I'm still a lil confused with the distinction between these two.

Thanks.
 
Hi Kevin, things changed alittle with the Phenom cpu's compared to the earlier A64's.

Hypertransport is still used to connect the cpu to the rest of the components like the northbridge and such. The definition of Northbridge is alittle different now. Many now call it the 'UnCore'. The Northbridge now comprises the memory controller, Level 3 Cache, and of course the main hypertransport bus. The Northbridge runs on its own power plane now and usually runs much slower than the cpu. It helps control power consumption but of course reduces performance since both the memory controller and L3 cache runs alot slower than cpu clockspeed. Before Phenom the memory controller ran at cpu clockspeed. Like the normal Athlon64, Phenom still uses the actual hypertransport bus speed to derives its clockspeed which has a reference clock of 200mhz. Raising the hypertransport reference clock will not only overclock the cpu but the northbridge as well (Since for example the memory controller uses the htt bus clock to derives its total clockspeed as well and like the cpu it multiplys the reference clock provided by the htt bus to determine its total clockspeed.)

I'm really not great at explaining things. I have it right in my head but I can't always put it in words. If there is something you want explaned better just lmk. 🙂


Jason
 
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formulav8 said:
Hi Kevin, things changed alittle with the Phenom cpu's compared to the earlier A64's.

Hypertransport is still used to connect the cpu to the rest of the components like the northbridge and such. The definition of Northbridge is alittle different now. Many now call it the 'UnCore'. The Northbridge now comprises the memory controller, Level 3 Cache, and of course the main hypertransport bus. The Northbridge runs on its own power plane now and usually runs much slower than the cpu. It helps control power consumption but of course reduces performance since both the memory controller and L3 cache runs alot slower than cpu clockspeed. Before Phenom the memory controller ran at cpu clockspeed. Like the normal Athlon64, Phenom still uses the actual hypertransport bus speed to derives its clockspeed which has a reference clock of 200mhz. Raising the hypertransport reference clock will not only overclock the cpu but the northbridge as well (Since for example the memory controller uses the htt bus clock to derives its total clockspeed as well and like the cpu it multiplys the reference clock provided by the htt bus to determine its total clockspeed.)

I'm really not great at explaining things. I have it right in my head but I can't always put it in words. If there is something you want explaned better just lmk. 🙂


Jason
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northbridge frequency is different from L3 cache frequency.
 
formulav8 said:
Hi Kevin, things changed alittle with the Phenom cpu's compared to the earlier A64's.

Hypertransport is still used to connect the cpu to the rest of the components like the northbridge and such. The definition of Northbridge is alittle different now. Many now call it the 'UnCore'. The Northbridge now comprises the memory controller, Level 3 Cache, and of course the main hypertransport bus. The Northbridge runs on its own power plane now and usually runs much slower than the cpu. It helps control power consumption but of course reduces performance since both the memory controller and L3 cache runs alot slower than cpu clockspeed. Before Phenom the memory controller ran at cpu clockspeed. Like the normal Athlon64, Phenom still uses the actual hypertransport bus speed to derives its clockspeed which has a reference clock of 200mhz. Raising the hypertransport reference clock will not only overclock the cpu but the northbridge as well (Since for example the memory controller uses the htt bus clock to derives its total clockspeed as well and like the cpu it multiplys the reference clock provided by the htt bus to determine its total clockspeed.)

I'm really not great at explaining things. I have it right in my head but I can't always put it in words. If there is something you want explaned better just lmk. 🙂


Jason
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Thanks for that! So what you are saying is when i OC the HTT, the NB will also OC? But my BIOS also has a NB speed adjustment independent of the HTT multiplier. So i can manually adjust down the NB speed. Any reason to do that?
 
Heat84 said:
I bought the Phenom II and the ASRock board. Thanks for the board suggestion.🙂
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Well, its 2 months later and that board won't OC the 965BE(125W) stably. I tried everything as suggested in this thread. It looks like I'm gonna have to get a new board. Maybe if I had mentioned I wanted to OC, formulav8 would've recommended a different board. Oh well, my fault I guess. Unless someone has a suggestion that hasn't been tried in that thread, I guess I'll get a new board.


I guess that board is only meant for OC'ing Phenom I's and Athlons. So does anybody wanna buy that board Or know anybody that wants to buy that board? I'm trying to set up an account on E-Bay, which I've never done before. What's a good starting price? Am I crazy to expect to get $50 for it?
 
Heat84 said:
Well, its 2 months later and that board won't OC the 965BE(125W) stably. I tried everything as suggested in this thread. It looks like I'm gonna have to get a new board. Maybe if I had mentioned I wanted to OC, formulav8 would've recommended a different board. Oh well, my fault I guess. Unless someone has a suggestion that hasn't been tried in that thread, I guess I'll get a new board.


I guess that board is only meant for OC'ing Phenom I's and Athlons. So does anybody wanna buy that board Or know anybody that wants to buy that board? I'm trying to set up an account on E-Bay, which I've never done before. What's a good starting price? Am I crazy to expect to get $50 for it?
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How high of an overclock are you trying to get out of the 965? It probably won't go over 4.0GHz on air, and 3.7 - 3.8 is far more likely.
 
Heat, if you got that 780 based Asrock board I doubt its the board itself thats the problem.

Especially if your ocing using multiplyers I don't see it being the mobo. Its most likely the chip, cooling, voltage settings, ect... thats the most likely problem and not the mobo itself. It is possible you got a subpar version of the board I guess.


Also, I should have clarified that I refer to htt as the base clock, or reference clock of 200mhz. (I'm to lazy to read over what I said previously with a fine-toothed comb.) 🙂 When you raise the base clock both the hypertransport bus and northbridge clock increases as well since their clockspeed is derived from the htt reference clockspeed.

The htt bus itself can run in sync, or async to the northbridge but only at a speed lower than the northbridge speed. In other words the hypertransport bus cannot run higher than the northbridge can..


PS: Heat, Just because you have a C3 revision doesn't mean you will get 4ghz stable. Many chips won't get there.


Jason
 
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Not every chip is the same. But if you do get a new board I hope its gets you where you want. And just because the heat temp isn't at 80*c doesn't mean it isn't impacting your oc's stability. Thats why water and of course sub-zero methods brings most people higher, and more stable oc's.


Jason
 
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