CPU advice for low power (wattage) PC

Forums › Desktop computing › CPU advice for low power (wattage) PC - i5 4570T or i5 4690T

Slain1

6 posts

Wannabe Geek

#149998 8-Jul-2014 01:33

I am in the process of building a mini itx pc in the in-win BQ656 case.

As this case is tiny and the PSU is only 120W I am building with aims of as much computing power as possible and as low power consumption as possible with out going to fanancial excess. (also hoping to save on the power bill)

To this end I am looking at the Haswell i5 4570T or 4690T.

The 4570T:
Dual core, hyperthreaded
2.9GHz normal, 3.6GHz Turbo
4MB L3 Cache
iGpu HD4600, 200MHz normal, 1.15GHz Turbo
35W Tdp

The 4690T has:
4 core
2.5GHz normal, 3.5GHz Turbo
6MB L3 Cache
iGpu HD4600, 350MHz normal, 1.2GHz Turbo
45W Tdp

The problem I have is that I am unsure how much the turbo feature plays in the operation of the cpu so how much difference does the 400MHz normal speed difference matter when the Turbo's are only 100MHz difference?

I have the same question in regards to the iGPU; 150MHz normal difference but only 50MHz difference in Turbo?

Then there is the 2MB cache difference how much of difference can that make?

If the normal speed differences are not so important due to the very minor Turbo difference then the 4 core 4690T would probably be the better choice?

The 4 core is also more costly and hard to find so I am trying to decide if the extra cost effort and 10W Tdp increace is worth it.

Advice on these processors would be most appreciated.

The intended use of this machine is some light gaming (games that are a few years old at lease and usually in the $10-$30 in places such as JBHifi) light to medium level 3D CAD work (Solidworks), heavy browsing using multiple browsers and many tabs often with multiple streamed clips running or buffering, media watching (1080p several clips at once) and possibly a little video encoding if I were to decide to get a usb hdTV reciever dongle (its intended primarily for use in conjunction with my TV).

gzt

15189 posts

Uber Geek

Lifetime subscriber

#1083924 8-Jul-2014 09:44

Toms hardware have comparison charts for different CPU/workload. Check it out.

if hardware charts show lower spec is adequate for the purpose then no need to buy the better one.

Imo buy the better CPU and set a maximum utilisation to reduce the top end power consumption. Can also disable cores if required.

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Slain1

6 posts

Wannabe Geek

#1084271 8-Jul-2014 17:50

Unfortunately the Tom's hardware charts make no mention of the any of the haswell 'T' processor variants or even the 'S' variants (at least that I could find).

As far as deciding the better chip bassed on specs go I have no Idea much the turbo speeds come into play and also the impact of having higher L3 cache as these the only real differences outside of the number of cores. Basically if the turbo has a really noticeable effect then the 4 core is probably the better choice for the multitasking capabilities, but if not the hyperthreaded 2 core would probably be better but also still unsure of the effect of the cache difference

For another option what would be the feasibility of under clocking the normal speed of a 'S' variant processor's normal speed while leaving the turbo high? is this even possible as I understand that only the 'K' variants are able to be overclocked and would it bring the electrical and Thermal power requirements down?

gzt

15189 posts

Uber Geek

Lifetime subscriber

#1084339 8-Jul-2014 20:01

I'd take a look at the main processors on the charts. Then make some educated guesses for the variants. I was going to take a quick look at the charts but TH is really slow here tonight for some reason. Also if you can find reviews for those procs, they may use some of the same benchmarks as TH, making a useful comparison.

PANiCnz

936 posts

Ultimate Geek

#1087214 11-Jul-2014 14:41

Would it not be easier just to buy a NUC? Doubt you're going to save much on the power bill.

Poll

340 posts

Ultimate Geek

#1087272 11-Jul-2014 15:49

Usually what happens for the turbo boost is full boost is 1 core, 2 cores it drops down by 100Mhz, 3 cores by 200Mhz more and 4 cores by 100Mhz further.
From the first review I've read comparing a 3570t to the 4690t has the difference being around 9-10%, usually the improvement going from ivy to haswell is around 4-5%, so my back of a napkin calculations puts the 4570t being about 4-5% slower than the 4690t for gaming when paired with a dedicated gpu so save the money and go with the 4570t.

If you're not pairing it with a graphics card then every little bit will count and i'd go for the 4690t as they're the same graphics chipset and higher clocks will make a difference.

If any of your programs utilise real cores better than hyperthreaded cores then the 4690t takes the cake again.

timmmay

19622 posts

Uber Geek

Trusted

Lifetime subscriber

#1087304 11-Jul-2014 16:20

I'd buy the four core one. Though in your position, doing CAD and gaming, I'd have bought a bigger case, a bigger power supply, and a dedicated video card. 120W seems really light for what you intend to do.