Overclock.net - An Overclocking Community - View Single Post - [Various] Ashes of the Singularity DX12 Benchmarks
View Single Post
post #1181 of (permalink) Old 08-28-2015, 07:39 PM
Hey I get one of these!
KyadCK's Avatar
Join Date: Aug 2011
Location: Chicago
Posts: 7,377
Rep: 313 (Unique: 219)
Originally Posted by Mahigan View Post

Originally Posted by KyadCK View Post

Some incorrect math in there.

990FX stock HT clock is 2.6Ghz but can on some motherboards be overclocked to ~3Ghz. They are not stock clocked at 3.2Ghz. They are also 16-bit links in each direction, not 32-bit. 10.4GB/s unidirectional.

PCI-e 2.0 is 500MB/s/lane pre-encode. That's 8GB/s pre-encoded on an x16, and 6.4GB/s post encode (8/10 encode rate). PCI-e 3.0 is 1GB/s per lane and 128/130 encode rate for just under 16GB/s.

The 990FX board with 3.0 adds a PLX chip on top of that. It takes 32 lanes of 2.0 and splits them into either x16 or x8/x8 of 3.0, including the encoding changes. Hance the latency.

Well if anyone did the math incorrectly it would be AMD. I took the 6.4 GT/s 990FX shot from their PR material. Based on Hardware secrets information, I simply did a 6.4*2 for 12.8 GB/s. If the boards do only function at 2600MHz, rather than 3200MHz according to the PR material, then I am not sure why they would have placed this slide in their information. It would therefore appear to be rather dishonest on their part.

They do use 3.2Ghz HT. Just not on 990FX. More of a server thing.

Just correcting some variables in your equations. Had to do all this math before for other reasons, it helps to have correct numbers, and I have quite a bit of experience with the chipset.

(15 items)
AMD Ryzen R9 3900X
Gigabyte X570 Master
AMD 5700XT PowerColor Devil
32GB G.Skill TridentZ Neo (2x16GB 3600Mhz/C16)
Hard Drive
Intel 900P 480GB
Power Supply
Corsair AX1200
Corsair H150i
Phanteks Evolv X
Operating System
Windows 10 Enterprise x64
2x Acer XR341CK
Corsair Vengeance K70 RGB
Corsair Vengeance M65 RGB
Sennheiser HD700
Sound Blaster AE-9
Audio Technica AT4040
▲ hide details ▲
KyadCK is offline