effect of HT LINK SPEED on performance - myth or reality???

[Urizen]

here's the problem: I have an AM2 CPU (the 4400+) that's meant for HT2000 (that's an HT link speed of 1000mhz ie. HT multiplier of 5x)

but my mainboard only supports HT1600 maximum (ie. HT link speed of 800mhz maximum ie. multiplier goes up to 4x only)
yeah that means a crappy board but one of the only few that still supports AGP


which means my current HT link speed is 800mhz only
(my CPU still runs at its stock 2300mhz speed though)


now a few days ago I read this article which basically states that HT link speed has virtually no effect on performance (even 3D)
so I felt kinda relieved, sure I couldn't get my Ht link speed to 1000Mhz but apparently that wouldn't have changed anything performance-wise



but then I came across a topic on this forum, and specifically this post where the author clearly states that not only is there a difference in performance between 800 and 1000mhz, but also that the difference is HUGE, which completely contradicts the previous article


so the question (for expert experts only) is : which of the two is right ? in the article I linked the reviewer states (and explains) why HT link speed has little to no effect, yet here we see just the opposite !!! so is this paranormal or is there another explanation ?



and if accordpower99's right and an HT of 800 really is crap, then this means my CPU is operating BELOW its potential and I really absolutely MUST find a way to bypass bios limitations & increase my HT speed to 1000mhz !
is there a windows utility that can do it ?
any help greatly appreciated !

 

[hat]

Can you drop your multiplier and raise the FSB to 250?

 

[Darknova]

Only in synthetic benchmarks does the HT link matter...even then it's no where near as much as you'd think he made it sound.

The HT link can go down as low as 750Mhz with a dual-core Athlon with no adverse effects.

You want to stay between 800 and 1000Mhz just to be safe though.

In the real world you will see no noticeable difference between 800Mhz and 1000Mhz

Hope that helps

 

[AphexDreamer]

When the guys says,

"no i finally found it man, my ht link speed at 1000mhz finally fixed it. I had it at 800 apparently, but eveythings great now!"

How do you know he is talking about performance increase, typical increasing the and bringing to normal the HT Link speed brings a huge amount of stability.

Maybe the guy was trying to overclock, it was not working, then brought the HT linkl speed to normal and it was stable again.

Simply said, HT link effect mostly Stabilty and practicly has no perfromance increase unless in help stabalize your CPU overclock in which case it aided to help increase the speed of the CPU whcih effected performance.

But, hey I'm no expert, thats just what I think is the case, besides I didn't even read the whole thread just one post that you gave me from it.

 

[Mussels]

back when i was AMD, i had my HT link from 2000 to 3000 (200 FSB to 300, without lowering it)

Wasnt very stable, but it wasnt any faster either - so i lowered it.

I dont think the speed difference will be that great, the guy who claimed it made a huge difference was probably from other factors - overclocking other components for example.

 

[theonetruewill]

I keep mine at 600, instead of 1000, because I actually find it faster- yeah it's odd but I have the proof with superpi. There is a pitiful synthetic performance difference for the people that have it higher (pm pos_pc) but there's no noticeable performance differnce in the realworld.

 

[cdawall]

i ran it between 600~1200 and i think i got a difference of .2s in superpi between the lowest and highest. it make almost no difference so dont worry about it.

 

[trog100]

yes anywhere between 600 and 1200 wont show any real difference.. higher just brings in possible instability with no gain..

trog

 

[Urizen]

thanx for the positive replies folx

Can you drop your multiplier and raise the FSB to 250?

maybe but I'm not sure what you mean by FSB here (looks like things are more complicated with recent AMD setups)

apparently there's two completely separate "base frequencies", one for RAM & one for the bus (HT)
then there's the CPU base clock but I'm not sure if it's the same as the RAM or the same as the HT base clock

here this is what Everest shows about my mainboard :

both ram and HT have a base clock of ~200mhz but it's not the same 200mhz

(the HT link is at 848mhz instead of 800 because I activated something called "AM2boost" option in bios)

 

[Urizen]

btw this is the topic I was talking about, it's still in the same page as mine, same section :
http://forums.techpowerup.com/showthread.php?t=50970&page=2

it's definitely a performance issue, at least that's what he says

Only in synthetic benchmarks does the HT link matter...even then it's no where near as much as you'd think he made it sound.

well he did say it was "day & night" in terms of performance (he didn't know why his games ran a lot slower with his new 6400+, and he was even about to reformat his hdd, it was that bad) then he went from 800 to 1000 & according to him there was a huge boost

How do you know he is talking about performance increase, typical increasing the and bringing to normal the HT Link speed brings a huge amount of stability.
Maybe the guy was trying to overclock, it was not working, then brought the HT linkl speed to normal and it was stable again.

no he said it fixed the "slow" problem - besides if it were about stability only then 800 would've been better than 1000, no? instead he went up from 800 to 1000

I dont think the speed difference will be that great, the guy who claimed it made a huge difference was probably from other factors - overclocking other components for example.

that's what I thought (hoped) at first but in the topic - I linked to it again - he definitely says his games were running a lot slower depsite his new CPU before he made that simple change in the bios

so...how come?

 

[accordpower99]

how about this tell me how to screen shot my bios, my mulitplier is at 16x bus speed 200, eveyrthing else auto except ht link.

nothing else has worked for me in overclocking thats why its still at stock settings. letme know how to screen shot if you dont believe me.

the night and day was the both games runing extemely choppy vs. nice and smooth after ht link set at 1000mhz

 

[xvi]

Download and run PerfMonitor from www.cpuid.com. Left click one of the bars and choose "HyperTransport bus 0 Bandwidth". If that maxes out, do anything you can to raise your FSB. Don't know what to say other than that.

 

[Mussels]

Download and run PerfMonitor from www.cpuid.com. Left click one of the bars and choose "HyperTransport bus 0 Bandwidth". If that maxes out, do anything you can to raise your FSB. Don't know what to say other than that.

you can SEE that? sweet! i'll try this out on my AM2 system.

with my housemate watching pokemon on the system, the HT0 went between 250 and 800 (of 2000)
Will have to test it with something else later, but that seems a great diagnostic and perfect for this thread. Thanks for linking that.

P.S the HT0 option is low down on the list - there are lots of options, so scroll down to find it.

 

[trog100]

that amd boost thing is some kind of auto overclocking.. it caused me problems till i turned it off..

u have a baseline clock (fsb) 200mhz.. memory.. cpu speed and htt speeds are controlled by that..

htt is 5 x baseline clock = 1000..

memory would be 2 x baseline clock = 400/800

cpu would be 15 x baseline clock = 3000...

if everything is on auto raising the baseline clock will increase the speed of the other three things..

on manual u can independently adjust the speed of the other three things..

messing with the htt speed on its own will not make any real difference to performance.. but if u raise the baseline clock too much without lowering the htt multiplier to x 4 it might cause instability issues..

trog

 

[Urizen]

messing with the htt speed on its own will not make any real difference to performance..

but then how d'you explain this :

how about this tell me how to screen shot my bios, my mulitplier is at 16x bus speed 200, eveyrthing else auto except ht link.

nothing else has worked for me in overclocking thats why its still at stock settings. letme know how to screen shot if you dont believe me.

the night and day was the both games runing extemely choppy vs. nice and smooth after ht link set at 1000mhz

see folks that's what I meant - that's also what he said in the other topic, he only changed the HT speed (from 800 to 1000), nothing else

which basically contradicts everything that's said on the net about HT speed not affecting performance, because according to his results not only does HT link speed affect performance but it also has a HUGE effect at least that's the only rational explanation, afaik

with my housemate watching pokemon on the system, the HT0 went between 250 and 800 (of 2000)

yeah me too

but isn't that bad news ? cos' this also suggest that HT link affects performance (unlike what many ppl think)

 

[Urizen]

Download and run PerfMonitor from www.cpuid.com. Left click one of the bars and choose "HyperTransport bus 0 Bandwidth". If that maxes out, do anything you can to raise your FSB. Don't know what to say other than that.

yeah it maxes out but only during CPU-intensive stuff like winrar archiving (with multithreading option on)

maybe an HT link of 1000Mhz is necessary for dual-core systems ?



I tried raising the FSB in bios

now the thing is my CPU is meant for 200 x 11.5

so I raised the FSB to 220 and lowered the multiplier to 10.5

it booted and sure enough the HT link speed was 880mhz



but then anything above 220mhz won't boot !
I tried 225x10 and it didn't boot
fortunately I had "boot failure guard" enabled, and when it did post then it showed a multiplier of...11.5 ! (and CPU frequency of 2.6Ghz or something !)
so basically when I raise the FSB above 220 then it ignores the manual multiplier settings & reverts back to the default 11.5



so looks like I'm stuck with a maximum FSB of 220mhz thus maximum HT of 880mhz





so is there any other way I can force an HT of 1000mhz ?

is there a utility to override bios HT multiplier settings & force it to 5x instead of 4x?

if I make a bios dump is there a simple way to add the 5x option ? (a bit crazy but I'm desperate now )

 

[trog100]

but then how d'you explain this :see folks that's what I meant - that's also what he said in the other topic, he only changed the HT speed (from 800 to 1000), nothing else

which basically contradicts everything that's said on the net about HT speed not affecting performance, because according to his results not only does HT link speed affect performance but it also has a HUGE effect at least that's the only rational explanation, afaik

i would make no attempt to explain that.. i know what i know.. i dont give too much credence to one guys post as to what happens for him.. attempting to explain the inexplicable is a fools errand..

trog

ps..u could turn of the stupid auto overclock thing if u still have it running..

 

[Urizen]

i would make no attempt to explain that.. i know what i know.. i dont give too much credence to one guys post as to what happens for him.. attempting to explain the inexplicable is a fools errand..

trog

ps..u could turn of the stupid auto overclock thing if u still have it running..

he'd have no reason to lie unless there's another explanation (I hope)



anyway, I usually leave AM2boost (auto-overclock) on as I've had no stability probs with it (even with memtest)
HOWEVER I had to turn AM2boost off to be able to manually overclock (FSB, etc.) so the results I mentioned before (about system going unstable when FSB went above 220mhz) were with AM2boost OFF

btw the maximum vcore bios lets me set is 1.3V
now I suppose the necessary voltage depends only on the CPU's baseline clock (and not the "overall clock" which is baseline x multiplier), right ? in other words for example 200x1 requires as much voltage as 200x20 ?
if so maybe that explains why it wouldn't boot above 220mhz, if you need more than 1.3V for high FSB speeds

 

[Mussels]

CPU voltage depends on the overall clock, not the HTT speed.

Motherboard (northbridge) voltage may need to increase as the HTT goes up. - also you may be overclocking your ram, so it will need more volts too.

 

[Urizen]

so a CPU setting of, say, 200x15 will need exactly the same voltage as 300x10 ?



iirc there's no "northbridge" or "chipset" voltage option in bios, only vcore, dram & AGP voltage



btw. when I changed the FSB, the RAM clock was unchanged (it stayed at 400mhz (or 800mhz, whatever))

maybe it's an HT thing, maybe with hypertransport the chipset & RAM clocks are independent

 

[PVTCaboose1337]

Ima give you a story. I have my CPU. I have the HTlink at like 500mhz during OCIng. I do some benchies. I raise the HT to 765. I do benchies. Almost the same. It is about a 3% difference for me. It is not a myth but on the quad core phenoms expect a 20% difference.

 

[Darknova]

so a CPU setting of, say, 200x15 will need exactly the same voltage as 300x10 ?



iirc there's no "northbridge" or "chipset" voltage option in bios, only vcore, dram & AGP voltage



btw. when I changed the FSB I remember that the RAM clock remained unchanged (it stayed at 400mhz (or 800mhz, whatever) regardless of FSB clock

maybe it's an HT thing, maybe with hypertransport the chipset & RAM clocks are independant

Yes, because the CPU is still running at exactly the same speed as it was before. 3Ghz.

A lot of boards (especially cheaper ones) don't give you that many options for overclocking. We're talking in general terms, but if there is no option then there's nothing you can do about it unfortunately.

I think you'll find that unless you have the RAM divider set to Auto then the RAM clock will have changed, but most RAM will overclock to some degree, and you didn't push it very far.

And no, everything is dependant on your bus speed. CPU, RAM, HT, everything.

 

[Urizen]

well I set the FSB values from 200mhz up to 220mhz and each time the RAM clock remained unchanged @ 400mhz (according to cpuz & everest)

however activating AM2boost does increase my ram clock by about 5% (as well as HT clock) but also disables manual overclocking

I haven't overclocked my RAM though (I set my DRAM voltage to "auto")

however my RAM is certified for 5-5-5 and I set its timings to 4-4-4 & it still works without a problem I dunno if decreasing timings counts as "overclocking" though

Ima give you a story. I have my CPU. I have the HTlink at like 500mhz during OCIng. I do some benchies. I raise the HT to 765. I do benchies. Almost the same. It is about a 3% difference for me. It is not a myth but on the quad core phenoms expect a 20% difference.

thanks m8 that's good news !


btw I just tried my own benches using 3Dmark05

I did all tests except the CPU ones (3Dmark05 doesn't use both cores)

I did the benchmarks using various HT link speeds from 200mhz up to 800mhz (checked in cpuz & everest to make sure new HT clock settings were applied)


the average FPS for most test didn't change at all regardless of HT clock

with the exception of one test, "vertex shaders - simple" (it's also 3dmark05's toughest test)
with this test, the average fps were as follows :
- HT clock @ 200mhz : 9fps
- HT clock @ 400mhz : 11fps
- HT clock @ 600mhz : 12fps
- HT clock @ 800mhz : 12fps (same as with 600mhz)

so apparently full potential is achieved at around 600mhz HT

I couldn't test it at 1000mhz but if performance is the same at 600mhz & 800mhz then it's likely it won't change at 1ghz



so you're probably right it only affects performance with quad-core & super-high-end CPUs but by the time I get one of these (not anytime soon) I'll have a new mobo & ram by then

PS. and I dunno what happened with accordpower99's setup but maybe it's cause he's got a top-line CPU over 3ghz and at those speeds HT link does have greater effect

 

[accordpower99]

PS. and I dunno what happened with accordpower99's setup but maybe it's cause he's got a top-line CPU over 3ghz and at those speeds HT link does have greater effect

OK UPDATE ON THIS I DUNNO WHAT MADE THE BIG CHANGE, I CHANGED IT BACK TO 800 AND GOT THE SAME PERFORMANCE, MAYBE THE AUTO WHICH KEPT IT AT 200? BUT THAT DOESNT MAKE SENCE, I DIDNT OC ANYTHING ELSE IM ALMOST POSITVE. SO TO EVERYONE

I SERIOUSLY THOUGHT THATS WHAT IT WAS, TRUST ME THERE WAS A BIG DIFFERENCE I JUST DONT KNOW WHAT IT WAS NOW.

 

[accordpower99]

Another Question Will The Htlink Make The Cpu Run Hotter?