Can timings effect the outcome of LinX

[BTRY B 529th FA BN]

I just did some testing with LinX on my Q9650 vs my i7 920, both @ 3Ghz

Q9650
5.5.5.15 @ 2T
Best time: 201.181
GFlops: 40.9476

i7 920
7.7.7.21 @ 1T
Best time: 209.773
GFlops: 39.2705

not only that, but the NB runs significantly hotter
Vcore is 1.20
Dram is 1.59
CPU VTT 1.27
NB Core 1.13

Room Temp: 75*F (ambients)
VREG(NB) 47*c
Core #0 67*c
Core #1 64*c
Core #2 66*c
Core #3 62*c

I am beginning to not like the i7 system and it starts with this RMA return board :\

 

[qazwsxokmijn]

I read somewhere that with HT turned on LinX results will show up as lower than it should be. In reality it's higher but for some reason I couldnt remember it shows a lower score.

 

[BTRY B 529th FA BN]

I read somewhere that with HT turned on LinX results will show up as lower than it should be. In reality it's higher but for some reason I couldnt remember it shows a lower score.

Yup. Confirmed.

HT ON
i7 920
7.7.7.21 @ 1T
Best time: 209.773
GFlops: 39.2705

HT OFF
i7 920
7.7.7.21 @ 1T
Best time: 187.873
GFlops: 43.8481

 

[Cogman]

I read somewhere that with HT turned on LinX results will show up as lower than it should be. In reality it's higher but for some reason I couldnt remember it shows a lower score.

HT adds overhead to parallel programs that use primary the exact same portion of the CPU. It makes single threaded apps slower, and can make multithreaded apps slower as well.

In other words, it isn't a magic bullet speed increaser. It has its place (running lots of different applications takes good advantage of HT). But the trade off is a decrease in performance for some apps.

 

[lopri]

Memory bandwidth definitely matters for Linpack. Timings affect bandwidth, so yeah they should matter in theory. HT of course does.




http://www.anandtech.com/show/3470

 

[qazwsxokmijn]

HT adds overhead to parallel programs that use primary the exact same portion of the CPU. It makes single threaded apps slower, and can make multithreaded apps slower as well.

In other words, it isn't a magic bullet speed increaser. It has its place (running lots of different applications takes good advantage of HT). But the trade off is a decrease in performance for some apps.

Yeah, that's what I was gonna say.