CPU decision

[13thmonkey]

OP. http://www.scan.co.uk/shop/computer-hardware/all/gpu-amd/radeon-hd7850-pci-e-(1024-cores)

£20-45 cheaper

 

[Idonno]

Normally I would say go intel for the better upgrade path and a more powerful processor but Intel SB chips only have 16pcie lanes whereas a 990FX has support for two GPU's in x16 or four in x8 mode which may come in handy if you run into the microstutter issue and the fix is to run 3 gpu's.

If your looking for pcie3 support then you have no choice but go intel and Ivy Bridge. Sandy bridge cpu's only support pcie2 but work fine in a pcie3 board.

Its a tuff call...

Actually you can run two cards at x16 on a LGA 1155 but, only with one board (that I know of). The ASUS P8Z77 WS LGA 1155 Z77 Here: http://www.newegg.com/Product/Product.aspx?Item=N82E16813131822

And here: http://www.youtube.com/watch?v=DNUph3VxNh0

With this board you get 4-PCI Express 3.0 x16 @ x16/x16/0/0 or x16/x8/x8/0 or x8/x8/x8/x8

 

[mouse24]

haaang on a second, just want to clear this up since I "think" this is how it works

Isn't if the board only has 8x/8x for pcie3 wouldn't that down convert to pcie2 @ 16x/16x with a non ivy bridge cpu?

 

[13thmonkey]

no, the sandy cpu can cope with n lanes, as the controller is on the cpu not the mobo. now x8 x8 (3) is the same bandwidth as x16x16 (2), but only if using pci-e3 cards (which probably need more bandwidth anyway)

 

[mouse24]

no, the sandy cpu can cope with n lanes, as the controller is on the cpu not the mobo. now x8 x8 (3) is the same bandwidth as x16x16 (2), but only if using pci-e3 cards (which probably need more bandwidth anyway)

Hmmm, interesting. One more question just for my own general understanding, it will always be an 8x/8x board since even though the load on the lane is lighter (theoretical, I know) with pcie 2 that still doesn't account for actual missing lanes, right?

 

[popatim]

Heres a benchamrk of an OC 8150 vs an OC'd 2500k.
It seems the i5 wins dispite only having 16 pcie lanes. I had thought the drop to x8 would help the amd close the gap in SLI ...
http://www.hardocp.com/article/2011/11/03/amd_fx8150_multigpu_gameplay_performance_review/1

 

[Idonno]

haaang on a second, just want to clear this up since I "think" this is how it works

Isn't if the board only has 8x/8x for pcie3 wouldn't that down convert to pcie2 @ 16x/16x with a non ivy bridge cpu?

no, the sandy cpu can cope with n lanes, as the controller is on the cpu not the mobo. now x8 x8 (3) is the same bandwidth as x16x16 (2), but only if using pci-e3 cards (which probably need more bandwidth anyway)

Not true. That would happen if the motherboard used the NF 200 chip but the ASUS P8Z77 WS motherboard has the new PCIe 3.0 PLX chip which enables it to run x16 @ x16/x16/0/0 or x16/x8/x8/0 or x8/x8/x8/x8 while maintaining PCIe 3.0 specifications without downgrading to PCIe 2.0.



AGAIN watch this video from Asus: http://www.youtube.com/watch?v=DNUph3VxNh0 Just because it hasn't been done before, doesn't mean it can't be done now. After all if technology was stagnant, it would kind of suck.

 

[adzx]

So, I shouldn't get an fx, and rather get a
2500k?
http://www.amazon.co.uk/Intel-Sandybridge-i5-2500K-Quad-Core-Processor/dp/B004FA8NX2/ref=sr_1_1?ie=UTF8&qid=1335602749&sr=8-1
And then OC it?

 

[13thmonkey]

Not true. That would happen if the motherboard used the NF 200 chip but the ASUS P8Z77 WS motherboard has the new PCIe 3.0 PLX chip which enables it to run x16 @ x16/x16/0/0 or x16/x8/x8/0 or x8/x8/x8/x8 while maintaining PCIe 3.0 specifications without downgrading to PCIe 2.0.



AGAIN watch this video from Asus: http://www.youtube.com/watch?v=DNUph3VxNh0 Just because it hasn't been done before, doesn't mean it can't be done now. After all if technology was stagnant, it would kind of suck.

Agree completely, to get more lanes you need a multiplexing chip.

 

[Idonno]

So, I shouldn't get an fx, and rather get a
2500k?
http://www.amazon.co.uk/Intel-Sandybridge-i5-2500K-Quad-Core-Processor/dp/B004FA8NX2/ref=sr_1_1?ie=UTF8&qid=1335602749&sr=8-1
And then OC it?

Yea, I think so and that seems to be the majority opinion here as well. OC if you want. The 2500k is very overclock friendly but, it's not necessary unless you want too.

 

[adzx]

Idonno, can your two 6870's support your 24" monitors at full resolution, texture etc?
If so what're your monitors resolutions?

 

[Idonno]

Yes, 3-duplicated or 3-extended @ 1920 x 1080 each or 3-eyefinity @ 5760 x 1080 (a little less than 5760 if you compensate for the bezels) and full everything for all use other than games. In games, it depends on the game. Some don't support eyefinity, some do.

As far as the games that do support eyefinity it really depends on the game BF 2 works great on the highest settings, where BF 3 needs to be dialed down a little.

I'm not much of a gamer though. I think the last time I played one was about 2 or 3 months ago. Every once and a while I get a little bored and play some for a couple of days then I leave them alone for a while.

My two 6870's in CF used to have micro-stutter and tearing issues. It wasn't that bad but, it was noticeable at times. Thankfully driver updates eventually solved those issues.

I was originally going to get a GTX 580 (the best card at the time) for this build Until I found out that two 6870's in CF out perform a 580 in overall benches for a lower price. Then I decided to go with the 3-24" monitors as well.

Two 6870's in CF have been great for me but if your a real hard core gamer you might want a little more card(s) for 3-24" monitors in eyefinity.

I've been thinking about selling one 6870 and replacing it with a 6870 x2, effectively giving me 3 way CF but like I said I'm not a hard core gamer and that decision is still up in the air.

Your 7850's are definitely stronger cards. I think you'll be pretty happy with them.

 

[adzx]

Alright, thanks for the info.