Processor Power vs GPU Power - How Much is Needed?

[Skippman]

Not being new to the PC building hobby I've often wondered how much processing power is REALLY needed to drive a GPU to its maximum performance levels. It seems most benchmarks done for video cards use the latest high end processors and RAM, likely as they're what’s available to the reviewer and because most enthusiasts crave the cutting edge.

But I wonder, do you really need a super powerful i7 processor to drive a set of say, 5870's or 5850's? Or could you get away with a lower end processor that you nearly max out when gaming.

What do you guys think?

[InspectahACE]

On those GPU's i doubt an i7 is really needed. I haven't play on anything other than the previous C2D's and the i7's so I can't say too much other than there was a good difference in my eyes. I'd say that's more due to going from a dual core to a quad core, and alot of the games I play are made for multi-core tech. Stick with a quad core regardless of series/brand and you should be ok.. Just my thought.

[Skippman]

For my next build, Project Monolith, I'm trying to decide between a Phenom II X4 955 Black Edition and the 1090 hex core processor.

[skier]

For my next build, Project Monolith, I'm trying to decide between a Phenom II X4 955 Black Edition and the 1090 hex core processor.

depends if you want the processing power comparable to an i5 or to an i7 (1090 is comparable to an i7 860, though the i7 has the same horsepower at slightly lower clocks (~15% lower clocks, and same deal for a 965 vs C2Q))

[Skippman]

That's my point though. I don't do folding or anything truely CPU intesive. All of my use is GPU intensive. So how much CPU do I really need to deliver the data to the GPU's fast enough? You see my problem. In the end I'll likely just get the 1090 because it's not much more expensive for 2 more cores. But I'd like to know the Phenom II is still an option.

[hnzw_rui]

Tom's actually has a pretty nice series on building a balanced gaming PC. It basically varies per game but all in all, no, you don't need a Core i7 nor a 1090T for a single GPU configuration. From the results, the Thuban worked the same as Deneb clock for clock. No benefit whatsoever from the two add'l cores.

[Skippman]

I was planning on a twin 5850 setup at some point, say 4 months down the line when the price drop happens. I've not selected the specific card yet but I'm likely going to stay reference this time after the issue I had with my Power Color 4870's so I can use water blocks on them this time. I'm trying to apply the skills I learned building WarMachine 2.0 to building this rig. I don't NEED a faster PC right now so I can take my time and select my parts carefully.

When Crysis 2 comes out I'd like to be able to run it at a decent frame rate and with a good resolution. I know how murderous Crysis was on PC's and consider it probably the most agressive benchmark in PC gaming right now.

A lot of my design is coming from my scrapped plan for WarMachine 3.0. The parts list I originally had for that was:

Case Corsair Obsidian CC800DW
PSU Corsair CMPSU-1000HX
Radiator 1 XSPC RX360 Triple Rad
Radiator 2 XSPC RX240 Double Rad
CPU Waterblock EK's Waterblocks EK-Supreme LT-775/1366 - NK-AC
Pump Innovatek Eheim HPPS i High Power 12V (501280)
Motherboard MSI 790FX-GD70
CPU AMD Phenom II X4 965 Black Edition Deneb 3.4GHz
RAM G.SKILL 2X Ripjaws Series 4GB (2 x 2GB) DDR3 1600 CAS 7
GPU Sapphire 100281SR Radeon HD 5870
Hard Drive Western Digital WD6401AALS 640GB 7200RPM x 3
Optical ASUS BC-06B1ST Blu-Ray


I've since decided to start with the Corsair 700D Obsidian case I was able to get for an excellent price. I'm still suck on motherboard choices but the Asus Crosshair IV seems to be the best choice for my needs although I'm not crazy about the software EAX. I'm not sure what to do about RAM and GPU at this point. I would want a minimum of 8GB of RAM and I'm thinking the 5850's might be enough power to do what I want to do.

[skier]

if you're doing really power heavy applications (Photoshop/Premiere/video edit/encoding etc.) and just gaming or daily driving then the quad is fine, and 8GB RAM is still more than enough (i use photoshop a fair bit and really dont need more than the 4GB i have) - a CL7 kit is great though, i have CL9 ripjaws i run at CL8

make sure you consider the GA-890FXA-UD5, at $180 and Gigabyte makes great boards (havn't been disappointed or wanted more from any of my GA-boards)

just make sure you bump whatever chip you get to at least 215 Bus as most any Phenom II will run at 220MHz without changing voltages (unless you want to change multi's instead, i've never actually had an unlocked multi) and most single threaded apps like a higher frequency ;)

[Skippman]

I've heard good things about Gigabyte boards in the past but, this is going to sound stupid, MAN are they ugly! Pastal blue?really? The ASUS board is a dedicated enthusiast board and is possbly the second most evil looking motherboard I've ever seen after the eVGA Classified series of boards. I know EKS has a waterblock for the Crosshair IV but I don't know if anyone makes one for the Gigabyte board.

[skier]

meh, i actually like the colors (or don't mind at least)

yeah, red & black is nice but i can't see paying more than $200 for an AMD board, i'll take the lower price and same performance/reliability/overclockability of the UD5 any day (both have 2 x16 @x16 with additional @x8 and @x4 slots) if you dont mind paying that much extra, the crosshair IV is a great board with a few extra features (tri-xfire) and does look sweet

[Major_A]

If you are gaming at 2560 then the CPU plays less of a role. Where the faster CPU helps, in gaming anyway, is at lower resolutions with lower detail settings.

[Skippman]

If you are gaming at 2560 then the CPU plays less of a role. Where the faster CPU helps, in gaming anyway, is at lower resolutions with lower detail settings.

I've no reason to doubt what you're saying but that seems paradoxial. I don't plan at running anything less that 1920x1200 on the machine ever. At one point this was considered ultra high rez but with the larger displays coming out I can see how the new benchmark has been moved up to 2560.

I need to do more research on the RAM to and how it works with the AMD processor. I confess I've not owned a desktop AMD proc since the Athlon 64 came out. I know with the memory controller being on the CPU itself this changes how your clock timings work.

[Major_A]

At that resolution and settings you're just relying on the GPU more than the CPU. The only place you might see some improvement with a faster processor is with the minimum frame rates. But at this resolution that could mean the difference between unplayable and playable.

God, I hate posting this but here's an article on Tom's. Keep an eye out for the higher resolution/detail tests.
http://www.tomshardware.com/reviews/cor ... 588-6.html

[Skippman]

That's an interesting article. Thanks for posting that Major. That's the exact GPU I plan to use and I wonder how much adding a second GPU will impact these numbers in the future. That being said the article does reaffirm to me that using the 956 Black Edition and over-clocking it might give me the best performance for the price. The hex core processors are cool, but given this machine will be predominately used for gaming it seems to be unnecessary.

On RAM I'm still stuck between the Ripjaws and the Corsair Dominators. The Corsair memory looks better, has excellent performance, but is far more expensive than the Ripjaws. I'm building this machine as much for aesthetics as I am for performance. The reviews of the memory on NewEgg cause me some concern though with people reporting the Corsair RAM not posting the specs it's rated to have.

[skier]

That's an interesting article. Thanks for posting that Major. That's the exact GPU I plan to use and I wonder how much adding a second GPU will impact these numbers in the future. That being said the article does reaffirm to me that using the 956 Black Edition and over-clocking it might give me the best performance for the price. The hex core processors are cool, but given this machine will be predominately used for gaming it seems to be unnecessary.

On RAM I'm still stuck between the Ripjaws and the Corsair Dominators. The Corsair memory looks better, has excellent performance, but is far more expensive than the Ripjaws. I'm building this machine as much for aesthetics as I am for performance. The reviews of the memory on NewEgg cause me some concern though with people reporting the Corsair RAM not posting the specs it's rated to have.

p1: agree
p2: all i know is my 1600MHz CL9 ripjaws run at 1730MHz CL9 or ~1450MHz CL8 right around stock 1.5v (1.53v for 1730MHz) but then again they really dont like anything higher than 1.545v or any lower than 1.5v

[Major_A]

I'm all about getting the most for my money, but why AMD? I know overall the platform is cheaper, is there any other reason?

[skier]

overall the platform is cheaper

.

[Major_A]

Point taken.

[Skippman]

I've been happy with my current setup and got a wicked high clock out of the E6600 I'm using right now but like skier said, the AMD platform is FAR cheaper. Since my application use tends to be nearly gaming exclusive there's no reason for me to go i7 or i5. While they both have very impressive heat numbers thanks to their small die size the AMD is comperable if not faster in many of the applications I'll be running. Plus given the memory controller is in the processor unless I'm mistaken I don't have to worry about overheating the northbridge as much on an AMD system.

I'm not really a fan boy or a loyalist other than when it comes to GPU's. I've had to many bad experiences with nVidia GPU's to go back. That being said, I'll also never buy a non-reference designed GPU again. I've had many problems with my PowerColors due to memory clock mismatches when running in Crossfire mode. I just feel like it's time for me to give AMD another shot.

[Skippman]

Poking around on the web I found even more information on my answer here.

Basically by stepping up the processor from 2.6G to 3.8G only yielded on average a 4 frame per second improvement when running two 5850's in Crossfire mode. This further proves my suspicions that for a gaming PC you don't need the latest cutting edge i5/i7 processor to drive the GPU's to max. This defiantly makes my choice this time to go AMD seem more reasonable and economical. I can spend the money I'd use on a faster CPU and more expensive board on other things like water cooling parts or more RAM.