Hyperthreading or not for old Xeons

[THORs_Hand]

Hello! 

 

I recently made a gaming rig from an old Dell PowerEdge T610 server that has 24GB of DDR3 ECC RAM, dual Intel Xeon E5645 2.4GHz 6 core 12 threads CPU and some other stuff, plus a Radeon Rx570 4GB GPU I slapped inside (via a PCIe x8 slot, some of you may know that the T610 doesn't have any x16 slot) 

 

Now, my question is, I have 12 physical cores, do I need hyperthreading? I mean 12 cores are enough for games, cad, physics simulations I do and some other stuff, like coding. Would disabling hyperthreading improve my single threaded performance? 

I do expect losing some points in multi threaded workloads, am I wrong? Going from 24 threads to 12. 

 

Like I see it suffer especially in games from poor single threaded performance, since not all games I have are really multi threaded

 

Thank you for any advice on improving performance a bit. 

 

P.S. I can't overclock anything. 

[Radium_Angel]

1 minute ago, THORs_Hand said:

P.S. I can't overclock anything. 

I've done the same with PE servers, while you *can* turn off HyperThreading, I don't think this will help any. Those old Xeons, despite the number of cores you have, are pretty old, going on 10 years old shortly, and just can't keep up.

 

[Bombastinator]

Part of the issue is specter/meltdown issues which attack hyperthreading and preemptive multitasking.  Older CPUs have protections if OSes are kept updated, but those protections work by turning off functions.  I don’t know how much performance your particular system lost.

 

these problems still plague even brand new system though it is claimed to a lesser degree.  Specter/meltdown are still not actually fixed though in amd64.  They’re merely mitigated.

[porina]

44 minutes ago, THORs_Hand said:

Now, my question is, I have 12 physical cores, do I need hyperthreading? I mean 12 cores are enough for games, cad, physics simulations I do and some other stuff, like coding. Would disabling hyperthreading improve my single threaded performance? 

The short answer is... maybe. Depends on the game and OS, how aware it is of HT. Best I can say is try it and see if it helps for what you do.

[THORs_Hand]

16 minutes ago, porina said:

The short answer is... maybe. Depends on the game and OS, how aware it is of HT. Best I can say is try it and see if it helps for what you do.

I just did the testing, seems quite odd though

For testing i used Cinebench R15, task manager in the foreground, same processes in background

with HT disabled i got:
58.9FPS in OpenGL (98% Ref. match) although the GPU wasn't having any trouble and i think it would have been able to pump out at least double FPS (50% utilization on it)

859CB points in multi threaded 
82CB in single threaded
MP Radio: 10.49

with HT enabled i got:

 

64.23 FPS for OpenGL (still 98% ref. match)

1104CB points in multi threaded
81CB points in single threaded
MP Radio : 13.56

It seems odd, HT makes the OS/programs see one core as 2 cores, that could also mean the performance is halved since one core would execute instructions for 2.

Seems like that's all the performance i can milk from these old Xeons though :))
Maybe i should upgrade to a Xeon X5680. According to Dell, it's the best Xeon this motherboard supports. the're a bit expensive for a 10 year old CPU though especially when you want 2 of them

[porina]

2 hours ago, THORs_Hand said:

I just did the testing, seems quite odd though

For testing i used Cinebench R15, task manager in the foreground, same processes in background

I realised I mis-read the question. If you only look at using 1 or all threads, Cinebench is indicative. What I had in mind wasn't what you asked directly. Since you mentioned games, I was thinking of the scenario where you're using more than 1 thread, but nowhere near all the threads of the CPU. It was that scenario I was thinking that might benefit from HT off in some cases.

[kidroc666]

Keep HT on those old xeon still are a powerful cup just the boards are so hard to get.

[Zando_]

On 11/2/2019 at 8:49 AM, THORs_Hand said:

Maybe i should upgrade to a Xeon X5680

X5690 is the best in socket (and should work, OEMs tend to just report what the best options were, not 100% of what the mobo can run). The X5675 is a much better value though, or the X5670 if you can take the slight clockspeed drop. Though like Radium said:

On 11/2/2019 at 7:36 AM, Radium_Angel said:

Those old Xeons, despite the number of cores you have, are pretty old, going on 10 years old shortly, and just can't keep up.

They're getting up there, around 8 years old now. At a well tuned 4.2-4.7GHz OC they can be decent, on the higher end they can almost match the cinebench score of a bone stock Ryzen 5 1600. Before Ryzen came out they were solid value, Zen smashed them though so they're mostly an enthusiast platform now. Depending on your budget, X79/X99 era Xeons and mobos could be within reach and they'll perform a lot better while keeping the HEDT features (or server ones if you get a server mobo). 

 

Basically these Xeons are quite old, an X5670-5690 could be a decent upgrade but it still won't do too well in modern games. If you're fine with lighter titles or low fps then they can be kinda decent in a few more titles (I pulled around 30-40fps in Assassin's Creed Odyssey, but my X5670 was overclocked to 4.54Ghz with RAM OCed to 2100Mhz or so at Cl10).