MYSTERIOUS 3400+, 800 HTT? What's that mean?

[CrunchTime]

Well after purchasing the 939s 3400+ and realizing its the exact same clock speed as the 939 slot 3500+, i did a seach and found out that the only difference is in the HTT bus. It says its limited to 800 HTT, but what does that really mean? Does that mean its just like an Intel 800Mhz Bus? Hopfully this thing is overclockable past 200Mhz... I have some Corsair PC4400 !

Im switching over to AMD from Intel which is basically why I am confused. If someone has any knowledge of this 3400+ let me know, and can explain this whole Hypertransport thing

http://www.newegg.com/app/viewProduc...ion=19-103-503

[mcnbns]

HyperTransport is kinda like FSB in non-A64 systems. Multiply HTT speed by multi to make CPU clock speed, but if you multiply the HTT speed by the LDT multiplier (usually 2,3,4 or 5) you get the overall HTT speed. The new 3400+ just has a slightly limited overall HTT speed, which probably won't make much of a difference in real-world performance, if it makes a difference at all. However, the weird thing about HTT is that it is used instead of a traditional north bridge. The northbridge and memory controller are located in the CPU itself, instead of in the motherboard, eliminating a major bottleneck. The HTT speed governs how much theoretical bandwidth there is between your CPU and RAM, basically. The difference between an HTT speed of 800 and 1000MHz should not be very evident.

Any A64 owners out there feel free to correct me if I'm wrong.

EDIT: Here's a link that will probably explain it better than I did. http://www.ocforums.com/showthread.php?t=306418

[CrunchTime]

awesome, that explains it. yeah, i dont see how 800HTT from 1000 could create much of a diff. Is there a way to increase HTT through overclocking in any way?

[mcnbns]

Yeah, you can change the LDT multiplier in the BIOS or raise HTT speed. You should probably try to keep the HTT overall speed not too much over stock to maintain stability. If you get up into the 250+ range, you'll probably want to knock the LDT multi down to 3 (from 4).

Ask some people that have tried it, or do some benchmarks yourself and see if there's a difference between higher HTT speeds and lower ones (say, 800MHz and 1000MHz ). Have fun!

EDIT: Forgot to say that HTT overall speed increases as you overclock the HTT to get a higher CPU clock unless you lower the LDT multi. Confused yet?

[mcnbns]

Doh! There is a thread with benches at different HTT speeds stickied here! I assume you're slightly more observant than me, but here's the link, anyway. http://www.xtremesystems.org/forums/...ad.php?t=39559

[blinky]

HTT is set by the chipset isnt it?

[craig588]

Yes, it has nothing to do with the CPU. Even less so than the FSB has to do with the CPU in a Barton based system.

[hollywood]

READ

http://www.xtremeresources.com/forum...ad.php?t=34304


The S939 3400+ is identical to the 3500+ except it's HT link speed id restricted to 800MHz, instead of 1000MHz.

[CrunchTime]

Thanks guys. Well im not a "stupid" or newbie overclocker but I am to AMD.. just trying to collect as much info as I can before i get my new system

[craig588]

I have run all of my 754 chips well over 1GHz HTT. The officiall speed for the Barton is 166MHz, no one ever runs at that speed either. Even in that thread it shows people running at 255HTT with a 4X multi, that is once agian, above 1GHz.

[CrunchTime]

So... im assuming the HTT spead cannot be affected unless you have an engineering sample. Cool, the benchies in that one thread above deemed negligable results anyways at higher clock speeds. Cant wait to see how far I can go with my Corsair 4400

[CrunchTime]

Actually upon further looking: It seems that HTT is configurable via the bios, atleast with the ABIT AV8.. http://www.hardocp.com/image.html?im...8yMl9sLmdpZg==

Basically it seems you can overclock it to FSBx5 (1000) but its not "supported" ... thats where overclocking comes in

[s e t h]

so how does it run

[reject]

yeh, k8t800 pro boards can have 5x ldt multi as can some nf3 250s. but its easier to decrease multi than increase HTV if theres no performance increase

[CrunchTime]

so how does it run

Still waiting to get it newegg shipped today, will get it on Tuesday.

[OC Detective]

Do us a favour when you get it can you take a picture of the info on the cpu itself and then a screenshot of CPUID when installed. Some people on other forums still doubt the existence of this cpu!

[longshot]

Go to this link someone else allready has one and has CPUz screens.

http://forums.anandtech.com/messagev...yword1=3400%2b

[Geforce4ti4200]

I noticed no difference in performance and my 3dmarks didnt change one bit with 800 or 1000 HTT so it doesnt matter. However you should have gotten a winchester instead, its 5% faster clock for clock and the 3200+ is cheaper too and overclocks better.

[CrunchTime]

meh, i want a soc. 939 processor.

[Skeet]

well the winchester is a socket 939 cpu, they are released in lower modells too just like the s754. If I were you i'd get a winchester if you can find it for a good price(depending on where you live course)