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Intel Skylake / Kaby Lake

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Topweasel

Diamond Member
Oct 19, 2000
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I was looking specifically for Skylake-X comparisons. Specially the 8-10c units.

Sent from my Pixel XL using Tapatalk
 

Edrick

Golden Member
Feb 18, 2010
1,915
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It could be because core to core ping times are rather slow. Moving from Ring to Mesh seems to be causing problem especially in games. In Ryzen's case we learned that when certain threads were running on different CCX, there was very clear penalty for peformance. Atleast in Zen's case latency within one CCX was reasonably low for threads which has a lot of communication in between.

Unfortunately in the case of 7900x, there ain't a single core-pair with low latency.



https://www.pcper.com/reviews/Processors/Intel-Core-i9-7900X-10-core-Skylake-X-Processor-Review/Thread-Thread-Latency-and-
If it is this bad with the LCC die, I suspect it will be worse on the HCC and XCC dies.
 

lolfail9001

Golden Member
Sep 9, 2016
1,056
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If it is this bad with the LCC die, I suspect it will be worse on the HCC and XCC dies.
The idea here is that while it is worse on LCC, it scales way better than ring bus with core count.

Also, latency is higher, but so is bandwidth.
 

Wyrm

Junior Member
Jun 20, 2017
23
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Does anyone know the ETA of the official spec sheet leaks for i9 7920X and ThreadRipper chips? I need a lot of compute power and bandwidth for image processing but don't really want to do CUDA.
 

pantsaregood

Senior member
Feb 13, 2011
993
37
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It just occurred to me how absurdly bad the value of the i7-7740X is.

The i7-7740X retails for $349.99. The i7-7800X is $389.99. Seems like you'd be a fool to not throw down the extra $40.
 
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Jan Olšan

Senior member
Jan 12, 2017
266
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The Kaby-X OCs quite high reportedly, over 5 GHz. It's basically milking people who can't resist the offer of higher single-thread performance.
 

khon

Golden Member
Jun 8, 2010
1,319
124
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The i7-7740X would be so much better if it could be used with Z270 motherboards instead of X299. Why pay $100+ dollars extra for features you can't use ?
 
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crisium

Platinum Member
Aug 19, 2001
2,634
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Because part of the $100 goes to Intel. Gotta get ST performance chasers (gamers) who demand the best to go X299 if they want the extra few hundred MHz over their 7700k build. Then they buy a new board again for Coffee Lake.

I don't think many will do that. But who knows...

Edit: Real answer may that by taking out iGPU and having the physically socket bigger helps keep it cool and OC better. KBL-X on Z270 would only have 1 of those advantages.
 

wildhorse2k

Member
May 12, 2017
180
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It just occurred to me how absurdly bad the value of the i7-7740X is.

The i7-7740X retails for $349.99. The i7-7800X is $389.99. Seems like you'd be a fool to not throw down the extra $40.
I think with Skylake-X latencies the 7800X is a very bad choice. Power draw doesn't seem to go down significantly with lower core counts and latencies will stay. Due to high motherboard prices i7-7740X will make no sense either. Only 7820X and 7900X make sense.
 
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TheF34RChannel

Senior member
May 18, 2017
782
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Because part of the $100 goes to Intel. Gotta get ST performance chasers (gamers) who demand the best to go X299 if they want the extra few hundred MHz over their 7700k build. Then they buy a new board again for Coffee Lake.

I don't think many will do that. But who knows...

Edit: Real answer may that by taking out iGPU and having the physically socket bigger helps keep it cool and OC better. KBL-X on Z270 would only have 1 of those advantages.
Have they though? It seems to me they just disabled it.
 
Mar 10, 2006
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Have they though? It seems to me they just disabled it.
The die is identical to the one on KBL-S, the iGPU is just disabled. The changes are in the packaging (LGA 2066 package) as well as obviously the much more robust power delivery systems of your average X299 board vs your average, much cheaper LGA 1151 board.
 

TheF34RChannel

Senior member
May 18, 2017
782
301
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The die is identical to the one on KBL-S, the iGPU is just disabled. The changes are in the packaging (LGA 2066 package) as well as obviously the much more robust power delivery systems of your average X299 board vs your average, much cheaper LGA 1151 board.
Exactly, they really just have stapled KBL-S onto a different socket.
 
Mar 10, 2006
11,719
2,010
126
Because part of the $100 goes to Intel. Gotta get ST performance chasers (gamers) who demand the best to go X299 if they want the extra few hundred MHz over their 7700k build. Then they buy a new board again for Coffee Lake.

I don't think many will do that. But who knows...

Edit: Real answer may that by taking out iGPU and having the physically socket bigger helps keep it cool and OC better. KBL-X on Z270 would only have 1 of those advantages.
Coffee Lake-X will work in X299 boards :)
 

Timmah!

Senior member
Jul 24, 2010
735
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I could not care less about slightly higher latencies or worse gaming performance (when its excellent anyway), even higher power draw leaves me cold - i am annoyed with the fact (or should i say assumption, although very likely to be truth), that LCC die is just 10 cores, so if i would want 12-cores / 7920x (and i would, as it would nicely double my current core count), i would have to be satisfied with the most cut down version of the HCC die.

That sucks and i am not sure if i wont rather save 200 bucks and get just 7900x, which is a nice full fat die. On other hand, its just 10 cores - for a grand, when i can have 8-core Ryzen for as low as 300.... And its only 4 more cores than i have now.

Then again, if the 7920x clocks as good as 7900x (or its capable of at least 4,5GHz on all cores)....could be worth it, even though it hurts my OCD :)

On another note, its funny how moods swing :-D I recall not so long ago people over here hated on Broadwell-E, as it could not even overclock as good as HW-E before it, nor had it Skylake-S´s sky-high IPC... so utter disappointment to everyone and their mothers. But luckily Skylake-X was coming, fixing both clocks and IPC, and adding new superb reworked cache system on top of it... that went well. Maybe BW-E was not so awful after all?
 
Aug 11, 2008
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I think we were expecting Skylake with more cores, that's what it is but not really, the changes to cache and the mesh arrangement seem to have a negative impact on significant cases, maybe gaming is another victim of it, but it seems Intel implies is more related to power management!?
another thing with Skylake that we would expect was good power usage, well, it's not here... combined with the TIM thing, it feels like the high clocks are a late reaction to competition!? or is it just inevitable because of the changes (cache, mesh...)?
still performance is there it's very strong most of the time, and if you are willing to invest on a really good cooler and delid (RIP warranty) it can OC quite far.. but it makes you wonder about the 18 core chip, is that thing going to be like the Xeons, 2.4GHz base clock or something?

also the high risk of killing the CPU when switching from Skylake to Kabylake is...

but 10 core drop in price from the 6950X looks good, even the 7800x looks like a good competitor to the Ryzen R7 (even 1700 OC), the problem is that when you factor the cost of motherboards, high end cooling, possible delid and so on not really, but if you are going for high end MB+cooler anyway the 7800x OC is probably the better choice


still, this is probably the worst Intel "HEDT" launch ever.
I would say broadwell E is the worst HEDT launch. No performance increase at all due to minimal ipc gain and poor overclocking. The performance is improved in most cases with Skylake X, but thermals and power usage need to be improved. Perhaps power usage and performance, especially in gaming, will improve as bioses mature. I am however mystified by the decision to use TIM. It is a disappointment to loyal intel users, and of course like throwing raw meat into a school of sharks to the crowd looking for any excuse to bash intel.
 

lolfail9001

Golden Member
Sep 9, 2016
1,056
353
96
Was is more so bandwidth that was the problem with the ring bus setup as core counts increased?
The issue was the fact that you had to add a second ring and buffer between them. That increased latency well over twofold. Now the highest latency on XCC won't go higher than ~160% of highest LCC one if my napkin math is correct.
 

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