Question about RAM

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schack
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Question about RAM

Post by schack » Wed Nov 06, 2019 3:26 am

Let's say I buy 2x16 and 2x8 dimms of the same ram - in this case, the Patriot Viper Steel Series - with same timings and tested frequency. I correctly install them on my B350 Prime Plus / Ryzen 1700 system. Is there any downside to doing this? Will I take a performance hit in any way?

Does dual channel / single channel make a difference for chess engines?

Thanks for any insight you can offer.

Zenmastur
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Re: Question about RAM

Post by Zenmastur » Wed Nov 06, 2019 6:52 am

schack wrote:
Wed Nov 06, 2019 3:26 am
Let's say I buy 2x16 and 2x8 dimms of the same ram - in this case, the Patriot Viper Steel Series - with same timings and tested frequency. I correctly install them on my B350 Prime Plus / Ryzen 1700 system. Is there any downside to doing this? Will I take a performance hit in any way?

Does dual channel / single channel make a difference for chess engines?

Thanks for any insight you can offer.
Unless the die class is identical you may run into timing issues. These can be fixed of course but it may require tweaking secondary or tertiary timings. If the dimms use different dies it can be more problematic so I don't recommend it for a NOOB. Performance hit if timings are close is minimal if done properly.

Single channel sucks! Always use dual channel when available. It effectively doubles the memory bandwidth!

Regards,

Zenmastur
Only 2 defining forces have ever offered to die for you.....Jesus Christ and the American Soldier. One died for your soul, the other for your freedom.

schack
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Re: Question about RAM

Post by schack » Wed Nov 06, 2019 8:58 pm

Ok, one more question, then.

Does Stockfish have to have hash tables in powers of 2 anymore? Or can I use, say, 12gb of ram for hash? (Or 48?) I know there was a commit last year that dealt with something related to this, but my understanding (despite not being a NOOB) is limited of such matters.

MikeB
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Re: Question about RAM

Post by MikeB » Sat Nov 09, 2019 5:19 am

schack wrote:
Wed Nov 06, 2019 8:58 pm
Ok, one more question, then.

Does Stockfish have to have hash tables in powers of 2 anymore? Or can I use, say, 12gb of ram for hash? (Or 48?) I know there was a commit last year that dealt with something related to this, but my understanding (despite not being a NOOB) is limited of such matters.
Yes, you can use 12 GB or 48 GB of Ram for hash , since this patch committed in Dec 2017.
https://github.com/official-stockfish/S ... /pull/1341

schack
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Re: Question about RAM

Post by schack » Sat Nov 09, 2019 1:56 pm

Well now I feel better about springing for the whole 64gb. :)

MikeB
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Re: Question about RAM

Post by MikeB » Sat Nov 09, 2019 2:51 pm

schack wrote:
Sat Nov 09, 2019 1:56 pm
Well now I feel better about springing for the whole 64gb. :)
Especially if you're doing deep deep analysis. People who know more than me, say Hash works best if there is some hash pressure, meaning that it gets at least 50-70% full. I'm not an expert, so I take their word.

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