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Does CPU Cache really matter?

Temi_D

Temi_D

Temi_D

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Hi guys
I do A LOT of screen recording and transcoding. I mainly use hypercam and the DIVX codec. About 4-5 months ago, I completed the system in my sig with the E6300 CPU that has 2MB of cache. The thing is that when i record at high resolutions, i.e 1920x1080+, many frames are skipped so the playback is faster than normal.

Also in task manager, my cpu usage is no where near 100%, usually 70-80% (while gaming and screen recording at the same time), so the problem isnt cpu speed neither is RAM and hdd speed. So the only other limiting factor i could think of was the CPU cache.

Does cache really make that much of a difference? Do i need a CPU with bigger cache like the E8xxx or Q9xxx CPUs? help!
 
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You know I had a really similar problem using CamStudio.

Although CPU usage wasn't at 100%, my "actual input rate" was always lower - much lower - than the rate I was recording at. This meant recording duplicate identical frames (wasted space).

Increasing the requested recording rate would increase the reported input rate a little, and stress the CPU a little more, but I'd never reach the requested rate.

If I requested 10 FPS, I'd get 7.
If I requested 20 FPS, I'd get 15.
If I requested 60 FPS, I'd get 25.

Numbers made up, but you see the problem.

I thought to myself, that if it was capable of recording at 25 FPS, why didn't it record at 10 FPS when I asked it to?

I never did solve that connundrum. But I moved to Camtasia, which seemed to be a better piece of software all round (but had its own problems.)
 
ive also tried camtasia and camstudio with similar results. I get the correct FPS at lower resolutions, its just when im recording at really high ones that it all starts go go wrong
 
A processor takes some input data, does some calculations on it, and returns the result. This result is also stored in the cache, so if the processor has to do the same calculation in the near future it can look up the answer (from cache) rather than work it out from scratch again.

Cache can't be a bad thing, but how much is useful depends on what the computer is doing. If every operation is unique, it won't help at all. If most of them are the same, it'll help loads.

I don't know if more cache would help you here, as I know nothing about your application. Does the problem become much worse/better if you change the processor frequency?
 
Temi_D said:
Does CPU Cache really matter?

I do A LOT of screen recording and transcoding.
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Hi Temi_D,

The short answer is it depends on what kinda tasks you perform on the computer and how your software uses the available hardware . . .

I have read that *most* audio and video applications do not benefit from added processor cache as they use streaming data i.e it's being fed direct to the processor across from the system memory . .

When the Data-Set the processor needs can fit into the processor's personal cache it will always be faster compared to getting it sent across from the main system memory!

All an end user needs to know is what sized data set their software is using and is it streaming or not. Personally I would work that out myself by testing two processors side-by-side and observe the differences . . . if I saw a noticable advantage to the processor with beefed up cache I would be happy to pay the premium, as it stands I personally cannot see the added benefit hence my choice of a L3-cachless processor!

ranaoverclockinprogress.gif
 
Big.Wayne said:
ranaoverclockinprogress.gif
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AthlonII x3?
Didn't know you can unlock cores on those as well.
Which model is that and how are you finding a performance with those?
Is that under water as well?

Sorry to jump in a thread like that I just somehow missed those...



-----------------------------------
NVM just found this model, still my other questions stand still, this looks like a bloody bargain for 55quid delivered from competitor !!
I was going to get a 550BE soon but this looks very interesting at this price mark.
 
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can unlock other cores on some chips. Others are genuine core failures, so just as someone has an athlonII, doesn't mean it's a quad with cores disables
 
Cache makes a huge difference to most encoding & or any other PC use you care to mention. 2Mb L2 cache is 4 years out of date now ;)

Get at least a Q9450 or higher with 12Mb L2 cache as that speeds up things a lot, not just encoding but gaming, ripping DVD's, encoding etc etc. 12MB can hold a lot more data in the L2 cache and the speed it can fetch & prefetch data to & from is faster as well due to better Intel tech on the cache algorithms ;)

E6300 was always a budget CPU the main reason CPU's with a lot of cache cost more is because they cost much more to make & offer much higher performance. Unless you get the stop watch out it may not be apparent straight away but surf the web whilst doing some heavy encoding or media ripping with no slowdown & receive emails, burn discs etc etc all at the same time you begin to notice the difference ;)
 
Now i have to choose between getting a new Q9550 cpu ~ £170 or
Get a new Core i7 setup: 2.88GHz i7 930 (when its out), X58 mobo, 6GB ddr3 RAM ~ £500
 
Temi_D said:
Now i have to choose between getting a new Q9550 cpu ~ £170 or
Get a new Core i7 setup: 2.88GHz i7 930 (when its out), X58 mobo, 6GB ddr3 RAM ~ £500
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Q9550 will last you at least 2 more years gaming wise.

If you can just update your motherboard bios & swap it then go for it as even though a Core i7 is much better still Q9550 is a pretty good upgrade & in 2 years much newer & faster CPU's will be out so X58 will be obsolete by then. Core i7 will be much better for encoding & all round multi-tasking but obviously the additional £330 to you for a new mobo + DDR3 + Core i7 HSF etc etc.

If you have the money then Core i7 is the best choice but like all PC upgrades you can get similar results on older hardware with much less money so only you can decide if the difference is worth the £330!
 
mmj_uk said:
As far as I know a reduction in cache size was what made Celeron's worse than Pentium's back in the day.
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Yep, I'm often swapping out early Socket 478 CPUs e.g. Celeron 2-2.6GHz 400FSB 128/256K Cache for P4 2.4c+ 800FSB 512K with HT - much much quicker. Even the earlier P4 2GHz 533FSB is quicker than a Celeron 2.6GHz 400FSB due to the cache being double.

In modern CPUs, like the Core 2 Duo range, the cache is a lot higher anyway, but 2mb is on the lower side (1MB per core). I found the E8400 a great chip as it had 6MB cache.
 
Uriel said:
Cache also seems to make quite a difference to minimum gaming framerates.

See http://www.bit-tech.net/hardware/cpus/2009/10/26/amd-athlon-ii-x4-620-cpu-review/1

The Athlon IIs have got pretty decent reviews from sites where average framerates are benched. Bit tech seem to take more notice of minimum framerates and you'll see that their review is less than glowing.
Click to expand...

Just looking at that review again and something smells fishy. They have a Phenom II x2 550 @ 3.1GHz beating a Phenom II x3 780 @ 3.5 Ghz in Crysis. That can't be right can it?
 
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