i7-5775C forgotten CPU

[Mark77]

Rarely see it talked about in any of the threads here, the Intel i7-5775C.  Performance numbers seem pretty good.  Fits into the Haswell boards. 

 

Were there really so few of them sold that nobody has one? 

[Herman Mcpootis]

i'm guessing the release of it was way too close to skylake.

[dantayy]

The performance of that CPU is close to the 6700k, that's interesting

[SnowyMus]

Despite being an unlocked desktop i7, it's not really mentioned that often for a few reasons. Unless you want to use the integrated Intel Iris graphics, you are better off spending less money and getting a Intel Core i7-4790K. Not only did the Intel Core i7-5775C cost quite a bit more at the time (and still does), but it runs at 3.3 GHz where the Intel Core i7-4790K starts at 4.0 GHz, requiring a little overclocking just to catch up in most cases. Lastly, Skylake's Intel Core i7-6700K ate it a few months later.

 

It was kind of a wasted opportunity given some of the architectural improvements, like the 14 nm process being used. It's a great CPU, but really bad planning on Intel's part.

[FPS-Russia]

I don't know anyone who even built a PC with it.

[Dabombinable]

39 minutes ago, Kavawuvi said:

Despite being an unlocked desktop i7, it's not really mentioned that often for a few reasons. Unless you want to use the integrated Intel Iris graphics, you are better off spending less money and getting a Intel Core i7-4790K. Not only did the Intel Core i7-5775C cost quite a bit more at the time (and still does), but it runs at 3.3 GHz where the Intel Core i7-4790K starts at 4.0 GHz, requiring a little overclocking just to catch up in most cases. Lastly, Skylake's Intel Core i7-6700K ate it a few months later.

 

It was kind of a wasted opportunity given some of the architectural improvements, like the 14 nm process being used. It's a great CPU, but really bad planning on Intel's part.

From what I can tell-Broadwell really doesn't respond well when you try to overclock it-unlike Haswell and Skylake (and from what I've seen, Skylake is the new Sandybridge with the way the majority overclocks)

[Jumper118]

I have an i5 5675c in my main rig at 4.2ghz for dailies. It's great

[porina]

I got an i5-5675C to play with, and it does some things amazingly, and some things not so well.

 

As already covered, it isn't an overclocker's dream. The default base clock of 3.1 GHz isn't much. My sample was Prime95 stable at 3.5 GHz 1.20v, 4.1 GHz 1.30v, and I couldn't stabilise 4.2 GHz 1.35v by which time the AIO watercooler was getting rather warm and I didn't push harder.

 

Where is does do well is in ram bandwidth limited compute applications. The L4 cache included in Iris Pro models, including the desktop chips, has a nominal peak bandwidth equivalent to about dual channel 3200 ram, with perhaps better latency too but I never checked that. For suitable compute tasks, it is practically ram unlimited compared to typical dual channel DDR3.

 

I did have an overclocking play, including the GPU to see what it does. In the end the bench system was running:

i5-5675C at 4.1 GHz

iGPU at 1250 stable (1300 was borderline unstable). Stock is 1100.

Ram was 1200 MHz (DDR3 2400) which is still important as the L4 cache still isn't big enough to deal with all the graphics needs.

 

Firestrike score was 1951 with iGPU at 1300, and TimeSpy score was 716 with iGPU at 1250, as that was more sensitive and prone to crash at 1300. For comparison, I got 753  in TimeSpy in another system with R7 260X.

7 minutes ago, Jumper118 said:

I have an i5 5675c in my main rig at 4.2ghz for dailies. It's great

What voltage and cooling did you use?

[SnowyMus]

6 minutes ago, Dabombinable said:

From what I can tell-Broadwell really doesn't respond well when you try to overclock it-unlike Haswell and Skylake (and from what I've seen, Skylake is the new Sandybridge with the way the majority overclocks)

That's what I've heard. In addition to the pretty significant 700 MHz disadvantage over the Intel Core i7-4790K, it sure didn't help. I kind of wonder if it's the heavier integrated graphics or something in the architecture itself.

[minibois]

It was pretty much Haswell-e performance (the i7 577C performed just as well as the i7 4790K) in CPU tasks, those CPU's were only (much) better in integrated GPU stuff, but most people don't really care about that.

 

I believe the CPU also came out at some weird time (maybe in the middle of the summer?) so many people missed the news. Not many people upgraded to it too, because they would just wait for Skylake.

[Jumper118]

16 minutes ago, porina said:

I got an i5-5675C to play with, and it does some things amazingly, and some things not so well.

 

As already covered, it isn't an overclocker's dream. The default base clock of 3.1 GHz isn't much. My sample was Prime95 stable at 3.5 GHz 1.20v, 4.1 GHz 1.30v, and I couldn't stabilise 4.2 GHz 1.35v by which time the AIO watercooler was getting rather warm and I didn't push harder.

 

Where is does do well is in ram bandwidth limited compute applications. The L4 cache included in Iris Pro models, including the desktop chips, has a nominal peak bandwidth equivalent to about dual channel 3200 ram, with perhaps better latency too but I never checked that. For suitable compute tasks, it is practically ram unlimited compared to typical dual channel DDR3.

 

I did have an overclocking play, including the GPU to see what it does. In the end the bench system was running:

i5-5675C at 4.1 GHz

iGPU at 1250 stable (1300 was borderline unstable). Stock is 1100.

Ram was 1200 MHz (DDR3 2400) which is still important as the L4 cache still isn't big enough to deal with all the graphics needs.

 

Firestrike score was 1951 with iGPU at 1300, and TimeSpy score was 716 with iGPU at 1250, as that was more sensitive and prone to crash at 1300. For comparison, I got 753  in TimeSpy in another system with R7 260X.

What voltage and cooling did you use?

1.325 and it does 4.3ghz at 1.35 but for some reason it throttles down at that speed event height the temps are fine.  The cooler is an alpenfohn matterhorn rev b

[porina]

45 minutes ago, Jumper118 said:

1.325 and it does 4.3ghz at 1.35 but for some reason it throttles down at that speed event height the temps are fine.  The cooler is an alpenfohn matterhorn rev b

Thinking more, if you use something like hwinfo64 or intel XTU you can possibly see if something else is limiting. I've hit current limit when overclocking Skylake and relaxing the limit allowed it to continue nicely. Symptom was above a certain multiplier it dropped back to stock clocks.

[Jumper118]

18 minutes ago, porina said:

Thinking more, if you use something like hwinfo64 or intel XTU you can possibly see if something else is limiting. I've hit current limit when overclocking Skylake and relaxing the limit allowed it to continue nicely. Symptom was above a certain multiplier it dropped back to stock clocks.

Mine only downclocks to 4.2 or 4ghz and the power limit in the bios was set to 4096w

[Jumper118]

18 minutes ago, porina said:

Thinking more, if you use something like hwinfo64 or intel XTU you can possibly see if something else is limiting. I've hit current limit when overclocking Skylake and relaxing the limit allowed it to continue nicely. Symptom was above a certain multiplier it dropped back to stock clocks.

Mine only downclocks to 4.2 or 4ghz and the power limit in the bios was set to 4096w

[porina]

4 minutes ago, Jumper118 said:

Mine only downclocks to 4.2 or 4ghz and the power limit in the bios was set to 4096w

Check current limit also? Separate item from power.

[Jumper118]

1 hour ago, porina said:

Check current limit also? Separate item from power.

Over 90000A

[Mira Yurizaki]

I think at around this time, the 5820K or whatever it was, the 6-score part, was out and was around the same price. And people were all "you should get this because 6-cores for the cost of a LGA115x i7!"

[Jumper118]

8 minutes ago, M.Yurizaki said:

I think at around this time, the 5820K or whatever it was, the 6-score part, was out and was around the same price. And people were all "you should get this because 6-cores for the cost of a LGA115x i7!"

Well tbh it was out just 2 weeks before skylake was more expensive then dc by a lot and it overclocks like poo. 

[NumLock21]

It was extremely expensive and Skylake was around the corner. The extra cost was for its Iris Pro graphics where no desktop users will care about. On mobile, maybe, desktops nope.

[porina]

13 minutes ago, NumLock21 said:

It was extremely expensive and Skylake was around the corner. The extra cost was for its Iris Pro graphics where no desktop users will care about. On mobile, maybe, desktops nope.

Locally to me the i5 and i7 Broadwell "C" processors were about the same cost as the equivalent Haswell "k" models. Given the rest of the platform was the same cost, it didn't make any difference. It was so close to Skylake anyone buying would already had the Haswell k or gone straight to Skylake, with too small a window in between for the Broadwell CPUs to go in numbers. The L4 cache that made Iris Pro work also worked on normal software. It is a good performance ram alternative providing the data set isn't too large, but at 128MB it does cover a lot more than the up to 8MB L3 of consumer CPUs.